Biocides and apparatus

ABSTRACT

A biocide is formed by mixing at least one of ammonium sulfamate and ammonium carbamate with an aqueous solution of a hypochlorite oxidant at a molar ratio of ammonium to hypochlorite of at least 1:1. The biocide is useful in treating microbial or biofilm growth, pulp and paper process water, cooling tower water, waste water, reclaimed waste water, sludge, colloidal suspensions, irrigation water or a medium having a reducing capacity.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/056,405, filed Feb. 14, 2005, which is a continuation-in-part ofPCT/IL2005/00007, filed Jan. 12, 2005 and claims the benefit of priorityfrom U.S. Provisional Patent Application Ser. Nos. 60/536,851,60/536,811, 60/536,853 and 60/536,852, all of which were filed on Jan.14, 2004. The contents of all of these applications are incorporatedherein by reference.

FIELD OF THE INVENTION

The invention relates to method and apparatus for inhibiting the growthof living organisms.

BACKGROUND

U.S. Pat. Nos. 5,795,487, 5,976,386, 6,110,387, 6,132,628, 6,429,181,6,478,972, and 6,533,958, British Patent No. GB 1600289, and publishedU.S. Patent Application No. 20030121868, the contents of all of whichare incorporated herein by reference, are believed to represent relevantprior art.

SUMMARY OF THE INVENTION

In some embodiments of the invention, there are provided methods forcontrolling microbial or biofilm growth in a medium. Common to theseembodiments of the invention, the medium is selected from the groupconsisting of pulp and paper factory process water, cooling tower water,waste water, reclaimed waste water, clay slurries, starch slurries,sludge, soil, colloidal suspension, and irrigation water, and stronglyreducing solutions, and the method comprises mixing anitrogen-containing compound having at least one primary, secondary ortertiary nitrogen atom, or a salt thereof, with a solution ofhypochlorite oxidant to form a biocide, the molar ratio of primary,secondary and tertiary nitrogen atoms in the at least one compound tohypochlorite being at least 1:1, and applying the biocide to the medium.

It will be appreciated that although the term “biocide” is usedthroughout the present description and claims, in some embodiments ofthe invention killing of microorganisms need not be effected in order toachieve control of microbial growth or biofilm growth.

It will also be appreciated that in some parts of the description andclaims, reference is made to a hypochlorite solution or to a solution ofhypochlorite, whereas in other parts of the description and claims,reference is made to a hypochlorite dilution which is prepared from ahypochlorite solution. Irrespective of the term used, in thoseembodiments of the invention in which hypochlorite is mixed with anitrogen-containing compound, the concentration of the hypochloriteshould not be higher than 24,000 ppm as total chlorine immediately priorto mixing with the nitrogen-containing compound.

It will be appreciated that the mixing of the compound containing atleast one primary, secondary or tertiary nitrogen atom, or salt thereof,with hypochlorite will take place in solution, and that in solution thecompound containing at least one primary, secondary or tertiary nitrogenatom, or the salt thereof, may be in equilibrium with an ionized,tautomeric or other form which is different than the form the compoundhas when not in solution. It will also be appreciated that when salts ofsuch compounds are used, in solution there may be equilibria involvingproton exchange between the components of the salt themselves and/orbetween one or more components of the salt and solvent. Thus, throughoutthe specification and claims, when reference is made to a compoundcontaining at least one primary, secondary or tertiary nitrogen atom, ora salt thereof, or to sub-groups of such a compound or a salt thereof,e.g. a compound of the formula R¹R²N-A-B or salt thereof, it will beunderstood that this expression is meant to encompass all protonated,de-protonated, and tautomeric forms of the compound or salt thereofwhich may exist in solution at the time of mixing with hypochlorite.

In some embodiments of the invention, a nitrogen-containing compoundwhich is an amphoteric molecule containing at least one moiety selectedfrom the group consisting of COOH and SO₃H and at least one moietyselected from the group consisting of a primary amine moiety, asecondary amine moiety, and a tertiary amine moiety is employed. Inother embodiments of the invention, an anionic form of such anamphoteric molecule is employed, and in some of those embodiments, thecounterion is of the form [NH₂R³R⁴]⁺, wherein R³ and R⁴ are definedbelow.

It will be appreciated that when reference is made to a salt of the formY^(x−)[NH₂R³R⁴]⁺ or Y^(x−)[NHR³R⁴Cl]⁺, and it is stated that Y is anacid, the acidity of this acid is considered in relation to the compoundNHR³R⁴.

There is provided, in accordance with an embodiment of the invention, amethod for controlling microbial or biofilm growth in a medium, themethod comprising mixing a salt of the formula Y^(x−)[NH₂R³R⁴]⁺ _(x) andan aqueous solution of a hypochlorite oxidant to form a biocide,

wherein

Y^(x−) is a basic form of an acid Y that contains at least one moietyselected from the group consisting of a primary amine moiety, asecondary amine moiety, a tertiary amine moiety, an amide moiety, animide moiety, a sulfamide moiety, a sulfimide moiety, and an amineiminemoiety; and

[NH₂R³R⁴]⁺ is an acidic form of a base NHR³R⁴ wherein:

R³ and R⁴ are each independently selected from the group consisting of Hand C₁₋₈ alkyl,

or R³ and R⁴, together with the nitrogen atom to which they areattached, form a 5- to 10-member heterocyclic ring optionallysubstituted by one or more groups selected from C₁₋₆ alkyl, C₃₋₈cycloalkyl, halogen, hydroxy, —OC₁₋₆ alkyl or —OC₃₋₈ cycloalkyl; and

x is 1 to 3;

and the molar ratio of [NH₂R³R⁴]⁺ to hypochlorite is at least 1:1,

and applying the biocide to the medium.

In accordance with some variations of this embodiment of the invention,Y is selected from the group consisting of straight, branched and cyclicmolecules containing at least one moiety selected from the groupconsisting of an amide moiety, an imide moiety, a sulfamide moiety, asulfimide moiety, and an amineimine moiety, and Y^(x−) is a basic formof the molecule. In some variations of this embodiment of the invention,in Y^(x−) at least one of the at least one amide moiety, imide moiety,sulfamide moiety, sulfimide moiety, or amineimine moiety is ionized tothe corresponding anionic form.

In accordance with some variations of this embodiment of the invention,Y is selected from the group consisting of amphoteric moleculescontaining at least one moiety selected from the group consisting ofCOOH and SO₃H and at least one moiety selected from the group consistingof a primary amine moiety, a secondary amine moiety, and a tertiaryamine moiety, and Y^(x−) is an anionic form of the amphoteric molecule.In some variations of this embodiment of the invention, at least one ofthe at least one COOH and SO₃H is ionized to the corresponding anionicform.

In accordance with some variations of this embodiment of the invention,Y^(x−) is of the formula [R¹R²N-A-COO]^(x−) or [R¹R²N-A-SO₃]^(x−),wherein:

A is a bond, straight-chain or branched C₁₋₂₀ alkyl, straight-chain orbranched C₂₋₂₀ alkenyl, straight-chain or branched C₂₋₂₀ alkynyl, C₃₋₁₀cycloalkyl, straight-chain or branched C₄-C₂₀ alkylcycloalkyl, C₄₋₁₀cycloalkenyl, C₄₋₁₀ cycloalkynyl, or C₆-C₁₀ aryl, wherein each C₁₋₂₀alkyl, C₂₋₂₀ alkenyl, C₂₋₂₀ alkynyl, C₃₋₁₀ cycloalkyl, C₄-C₂₀alkylcycloalkyl, C₄₋₁₀ cycloalkenyl, C₄₋₁₀ cycloalkynyl or C₆-C₁₀ arylis optionally substituted with one or more groups selected from —COOH,—COH, —SCH₃, —NH₂, ═NH, —NHC(═NH)NH₂, —OH, 4-hydroxyphenyl,5-imidazolyl, 3-indolyl, halogen, —SO₃H, ═O, C₁₋₈ alkyl, C₃₋₈cycloalkyl, C₄₋₉ cycloalkylalkyl, phenyl, 4-methylphenyl, benzyl,—O—C₃₋₈ cyclalkyl, —O—C₃₋₈ cycloalkyl, —O—C₄₋₉ cycloalkylalkyl,—O-phenyl, —O-4-methylphenyl, —O-benzyl, —SO₂R⁷ or —NHR⁷ wherein R⁷ isH, C₁₋₈ alkyl, phenyl, 4-methylphenyl, benzyl or —NH₂, and wherein eachC₁₋₂₀ alkyl, C₂₋₂₀ alkenyl, C₂₋₂₀ alkynyl, C₃₋₁₀ cycloalkyl, C₄-C₂₀alkylcycloalkyl, C₄₋₁₀ cycloalkenyl, C₄₋₁₀ cycloalkynyl or C₆-C₁₀ aryloptionally contains one to three heteroatoms selected from N, O and S;

R¹ and R² are each independently selected from the group consisting ofH, straight-chain or branched C₁₋₂₀ alkyl, straight-chain or branchedC₂₋₂₀ alkenyl, straight-chain or branched C₂₋₂₀ alkynyl, C₃₋₁₀cycloalkyl, straight-chain or branched C₄-C₂₀ alkylcycloalkyl, C₄₋₁₀cycloalkenyl, C₄₋₁₀ cycloalkynyl, or C₆-C₁₀ aryl, wherein each C₁₋₂₀alkyl, C₂₋₂₀ alkenyl, C₂₋₂₀ alkynyl, C₃₋₁₀ cycloalkyl, C₄-C₂₀alkylcycloalkyl, C₄₋₁₀ cycloalkenyl, C₄₋₁₀ cycloalkynyl or C₆-C₁₀ arylis optionally substituted with one or more groups selected from —COOH,—COH, —SCH₃, —NH₂, ═NH, —NHC(═NH)NH₂, —C(═O)NH₂, —OH, 4-hydroxyphenyl,5-imidazolyl, 3-indolyl, halogen, —SO₃H, ═O, C₁₋₈ alkyl, C₃₋₈cycloalkyl, C₄₋₉ cycloalkylalkyl, phenyl, 4-methylphenyl, benzyl,—O—C₃₋₈ cyclalkyl, —O—C₃₋₈ cycloalkyl, —O—C₄₋₉ cycloalkylalkyl,—O-phenyl, —O-4-methylphenyl, —O-benzyl, —SO₂R⁷ or —NHR⁷ wherein R⁷ isH, C₁₋₈ alkyl, phenyl, 4-methylphenyl, benzyl or —NH₂, and wherein eachC₁₋₂₀ alkyl, C₂₋₂₀ alkenyl, C₂₋₂₀ alkynyl, C₃₋₁₀ cycloalkyl, C₄-C₂₀alkylcycloalkyl, C₄₋₁₀ cycloalkenyl, C₄₋₁₀ cycloalkynyl or C₆-C₁₀ aryloptionally contains one to three heteroatoms selected from N, O and S;

or R¹ and A, together with the nitrogen atom to which they are attached,form a 5- to 10-member heterocyclic ring or a 5- to 10-memberheteroaromatic ring in which the free electron pair of the nitrogen atomto which R¹ and A is attached is not part of the aromatic pi-electronsystem, the 5- to 10-member heterocyclic or heteroaromatic ring beingoptionally substituted by one or more groups selected from C₁₋₆ alkyl,C₃₋₈ cycloalkyl, halogen, hydroxy, —OC₁₋₆ alkyl or —OC₃₋₈ cycloalkyl;

or R¹ and R², together with the nitrogen atom to which they areattached, form a 5- to 10-member heterocyclic ring or a 5- to 10-memberheteroaromatic ring in which the free electron pair of the nitrogen atomto which R¹ and A is attached is not part of the aromatic pi-electronsystem, the 5- to 10-member heterocyclic or heteroaromatic ring beingoptionally substituted by one or more groups selected from C₁₋₆ alkyl,C₃₋₈ cycloalkyl, halogen, hydroxy, —OC₁₋₆ alkyl or —OC₃₋₈ cycloalkyl.

In accordance with some variations of this embodiment of the invention,the concentration of the hypochlorite oxidant in the aqueoushypochlorite oxidant solution immediately prior to mixing with the saltor mixtures of salts is not more than 24,000 ppm as total chlorine. Inaccordance with some variations of this embodiment of the invention, theconcentration of the hypochlorite oxidant in the aqueous hypochloriteoxidant solution immediately prior to mixing with the salt or mixturesof salts is not more than 12,000 ppm as total chlorine.

In accordance with some variations of this embodiment of the invention,the salt or mixture of salts is in an aqueous solution at aconcentration of 0.5-60% w/v immediately prior to mixing with thehypochlorite oxidant solution.

In accordance with some variations of this embodiment of the invention,the mixing takes place in a mixing chamber into and out of which thereis a continuous flow of water during the mixing.

In accordance with some variations of this embodiment of the invention,the biocide is applied to the medium substantially as the biocide isformed. In accordance with other variations of this embodiment of theinvention, the biocide is applied to the medium within 30 seconds offormation of the biocide. In accordance with other variations of thisembodiment of the invention, the biocide is applied to the medium within60 seconds of formation of the biocide. In accordance with othervariations of this embodiment of the invention, the biocide is appliedto the medium within 90 seconds of formation of the biocide. Inaccordance with other variations of this embodiment of the invention,the biocide is applied to the medium within 120 seconds of formation ofthe biocide. In accordance with other variations of this embodiment ofthe invention, the biocide is applied to the medium within 150 secondsof formation of the biocide. In accordance with other variations of thisembodiment of the invention, the biocide is applied to the medium within180 seconds of formation of the biocide.

In accordance with some variations of this embodiment of the invention,the mixing chamber is a conduit.

In accordance with other variations of this embodiment of the invention,the mixing takes place in a mixing chamber out of which there is not acontinuous flow of water during the mixing. In accordance with othervariations of this embodiment of the invention, biocide is applied tothe medium substantially immediately upon completion of the mixing. Inaccordance with other variations of this embodiment of the invention,the biocide is applied to the medium within 30 seconds of completion ofthe mixing. In accordance with other variations of this embodiment ofthe invention, the biocide is applied to the medium within 60 seconds ofcompletion of the mixing. In accordance with other variations of thisembodiment of the invention, the biocide is applied to the medium within90 seconds of completion of the mixing. In accordance with othervariations of this embodiment of the invention, the biocide is appliedto the medium within 120 seconds of completion of the mixing. Inaccordance with other variations of this embodiment of the invention,the biocide is applied to the medium within 150 seconds of completion ofthe mixing. In accordance with other variations of this embodiment ofthe invention, the biocide is applied to the medium within 180 secondsof completion of the mixing.

In accordance with some variations of this embodiment of the invention,the hypochlorite oxidant is selected from the group consisting ofalkaline and alkali earth metal hypochlorites, hypochlorites released towater from a stable chlorine carrier and hypochlorite formed in situfrom chlorine gas, and mixtures thereof. In accordance with somevariations of this embodiment of the invention, the stable chlorinecarrier is selected from the group consisting of trichlorocyanuric acid,dichlorodimethylhydantoin and monochlorodimethylhydantoin. In accordancewith some variations of this embodiment of the invention, thehypochlorite oxidant is selected from the group consisting of lithiumhypochlorite, sodium hypochlorite, calcium hypochlorite, magnesiumhypochlorite and potassium hypochlorite. In accordance with somevariations of this embodiment of the invention, the hypochlorite oxidantis sodium hypochlorite.

In accordance with some variations of this embodiment of the invention,R³ and R⁴ are both H. In accordance with other variations of thisembodiment of the invention, one of R³ and R⁴ is H and the other is not.In accordance with other variations of this embodiment of the invention,neither R³ nor R⁴ is H.

In accordance with some variations of this embodiment of the invention,Y is selected from the group consisting of carbamic acid, sulfamic acid,glycine, glutamine, arginine, histidine, and lysine, and mixturethereof. In accordance with some variations of this embodiment of theinvention, Y is selected from the group consisting of melamine, cyanuricacid, hydantoin, dialkyl hydantoin such as dimethyl hydantoin, biuret,succinamide, succinimide, creatine, and creatinine, and mixturesthereof.

In accordance with some variations of this embodiment of the invention,the molar ratio of [NH₂R³R⁴]⁺ to the hypochlorite oxidant is 1:1. Inaccordance with other variations of this embodiment of the invention,the molar ratio of [NH₂R³R⁴]⁺ to the hypochlorite oxidant is greaterthan 1:1.

In accordance with some variations of this embodiment of the invention,the concentration of the hypochlorite oxidant in the aqueoushypochlorite oxidant solution immediately prior to mixing with the saltor mixture of salts is not more than 24,000 ppm expressed as totalchlorine, and the mixing chamber comprises a conduit through which waterflows as the hypochlorite oxidant solution and the salt or mixture ofsalts are mixed. In accordance with some variations of this embodimentof the invention, the concentration of the hypochlorite oxidant in theaqueous hypochlorite oxidant solution immediately prior to mixing withthe salt or mixture of salts is not more than 12,000 ppm as totalchlorine. In accordance with some variations of this embodiment of theinvention, the solution of hypochlorite oxidant is prepared in situ inthe conduit prior to addition of the solution of the salt or mixture ofsalts to the conduit.

In accordance with some variations of this embodiment of the invention,the salt or mixture of salts is diluted prior to mixing with thehypochlorite oxidant.

In accordance with some variations of this embodiment of the invention,the biocide has a pH of between 8.0 and 11.5 immediately prior to beingapplied to the medium. In accordance with some variations of thisembodiment of the invention, the biocide has a pH of at least 8.5immediately prior to being applied to the medium. In accordance withsome variations of this embodiment of the invention, the biocide has apH of at least 9.0 immediately prior to being applied to the medium. Inaccordance with some variations of this embodiment of the invention, thebiocide has a pH of at least 9.5 immediately prior to being applied tothe medium. In accordance with some variations of this embodiment of theinvention, the biocide has a pH of at least 10.0 immediately prior tobeing applied to the medium. In accordance with some variations of thisembodiment of the invention, the biocide has a pH of at least 10.5immediately prior to being applied to the medium. In accordance withsome variations of this embodiment of the invention, the biocide has apH of at least 11.0 immediately prior to being applied to the medium. Inaccordance with some variations of this embodiment of the invention, thebiocide has a pH of no more than 11.5 immediately prior to being appliedto the medium.

In accordance with some variations of this embodiment of the invention,the medium is selected from the group consisting of pulp and paperfactory water, cooling tower water, waste water, reclaimed waste water,clay slurries, starch slurries, sludge, soil, colloidal suspensions, andirrigation water. In accordance with some variations of this embodimentof the invention, the medium is pulp and paper factory process water. Inaccordance with some variations of this embodiment of the invention, themedium is cooling tower water. In accordance with some variations ofthis embodiment of the invention, the medium is waste water. Inaccordance with some variations of this embodiment of the invention, themedium is reclaimed waste water. In accordance with some variations ofthis embodiment of the invention, the medium is a clay slurry. Inaccordance with some variations of this embodiment of the invention, themedium is a starch slurry. In accordance with some variations of thisembodiment of the invention, the medium is a sludge. In accordance withsome variations of this embodiment of the invention, the medium is acolloidal suspension. In accordance with some variations of thisembodiment of the invention, the medium is irrigation water. Inaccordance with some variations of this embodiment of the invention, themedium is a medium containing strong reducing agents or having a highreducing capacity, viz. an ORP of not greater than 150 millivolts.

In accordance with some variations of this embodiment of the invention,the hypochlorite oxidant and the salt or mixture of salts are mixed inthe absence of added bromide and the medium is substantially free ofadded bromide during application of the biocide. In accordance with somevariations of this embodiment of the invention, bromide is not added tothe medium as a component to supplement or enhance the biocide.

In accordance with some variations of this embodiment of the invention,the biocide is applied to the medium periodically with a duty cycle ofless than 1:2. In accordance with some variations of this embodiment ofthe invention, the biocide is applied to the medium periodically with aduty cycle of between about 1:5 and 1:10. In accordance with somevariations of this embodiment of the invention, the biocide is appliedto the medium periodically with a duty cycle of less than 1:10. Inaccordance with some variations of this embodiment of the invention, thebiocide is applied to the medium periodically with a duty cycle of lessthan 1:25. In accordance with some variations of this embodiment of theinvention, the biocide is applied to the medium periodically with a dutycycle of less than 1:50.

In accordance with some variations of this embodiment of the invention,the biocide is applied to the medium at a rate to maintain in thebiocide a stable pH of at least 8.0 as the biocide is produced.

In accordance with some variations of this embodiment of the invention,the concentration of the biocide immediately prior to being applied tothe medium is from 1000 to 12,000 ppm expressed as total chlorine.

In accordance with some variations of this embodiment of the invention,the medium has a pH of between about 5 and about 11.5 before the biocideis applied to the medium. In accordance with some variations of thisembodiment of the invention, the medium has a pH of between about 6 andabout 10 before the biocide is applied to the medium. In accordance withsome variations of this embodiment of the invention, the medium has a pHof between about 7 and about 9 before the biocide is applied to themedium.

In accordance with some variations of this embodiment of the invention,the concentration of the biocide in the medium, upon application of thebiocide to the medium, is 0.5-300 ppm expressed as total chlorine. Inaccordance with some variations of this embodiment of the invention, theconcentration of the biocide in the medium, upon application of thebiocide to the medium, is 1-10 ppm expressed as chlorine.

In accordance with some variations of this embodiment of the invention,the biocide is effective within 24 hours of application to the medium.In accordance with some variations of this embodiment of the invention,the biocide is effective within 1 hour of application to the medium. Inaccordance with some variations of this embodiment of the invention, thebiocide is effective within 20 minutes of application to the medium. Inaccordance with some variations of this embodiment of the invention, thebiocide is effective within 15 minutes of application to the medium.

In accordance with some variations of this embodiment of the invention,the biocide is capable of reducing microbial activity by at least 50%within 3 hours after administration. In accordance with some variationsof this embodiment of the invention, the biocide is capable of reducingmicrobial activity by at least 50% within 1 hour after administration.In accordance with some variations of this embodiment of the invention,the biocide is capable of reducing microbial activity by at least 50%within 30 minutes after administration. In the context of thesevariations of this embodiment of the invention, reduction in microbialactivity may be correlated to an increase in operational efficiency ofthe system being treated. For example, in a paper machine, a reductionin microbial activity will result in improved runnability of the papermachine. In some contexts, reduced microbial activity can be correlatedto decreased production of ATP or to decreased production of catalase.In accordance with some variations of this embodiment of the invention,after the recited time period there is a residual of biocide, expressedas total chlorine, of at least 0.5 ppm. In accordance with somevariations of this embodiment of the invention, after the recited timeperiod there is a residual of biocide, expressed as total chlorine, thatis too low to be measured. In accordance with some variations of thisembodiment of the invention, the reduction of microbial activity ismeasured in a test sample. In accordance with some variations of thisembodiment of the invention, the reduction of microbial activity ismeasured on site.

In accordance with some variations of this embodiment of the invention,the biocide is capable of reducing microbial activity by at least 75%within 3 hours after administration. In accordance with some variationsof this embodiment of the invention, the biocide is capable of reducingmicrobial activity by at least 75% within 1 hour after administration.In accordance with some variations of this embodiment of the invention,the biocide is capable of reducing microbial activity by at least 75%within 30 minutes after administration. In the context of thesevariations of this embodiment of the invention, reduction in microbialactivity may be correlated to an increase in operational efficiency ofthe system being treated. For example, in a paper machine, a reductionin microbial activity will result in improved runnability of the papermachine. In some contexts, reduced microbial activity can be correlatedto decreased production of ATP or to decreased production of catalase.In accordance with some variations of this embodiment of the invention,after the recited time period there is a residual of biocide, expressedas total chlorine, of at least 0.5 ppm. In accordance with somevariations of this embodiment of the invention, after the recited timeperiod there is a residual of biocide, expressed as total chlorine, thatis too low to be measured. In accordance with some variations of thisembodiment of the invention, the reduction of microbial activity ismeasured in a test sample. In accordance with some variations of thisembodiment of the invention, the reduction of microbial activity ismeasured on site.

In accordance with some variations of this embodiment of the invention,the biocide is capable of reducing microbial activity by at least 90%within 3 hours after administration. In accordance with some variationsof this embodiment of the invention, the biocide is capable of reducingmicrobial activity by at least 90% within 1 hour after administration.In accordance with some variations of this embodiment of the invention,the biocide is capable of reducing microbial activity by at least 90%within 30 minutes after administration. In the context of thesevariations of this embodiment of the invention, reduction in microbialactivity may be correlated to an increase in operational efficiency ofthe system being treated. For example, in a paper machine, a reductionin microbial activity will result in improved runnability of the papermachine. In some contexts, reduced microbial activity can be correlatedto decreased production of ATP or to decreased production of catalase.In accordance with some variations of this embodiment of the invention,after the recited time period there is a residual of biocide, expressedas total chlorine, of at least 0.5 ppm. In accordance with somevariations of this embodiment of the invention, after the recited timeperiod there is a residual of biocide, expressed as total chlorine, thatis too low to be measured. In accordance with some variations of thisembodiment of the invention, the reduction of microbial activity ismeasured in a test sample. In accordance with some variations of thisembodiment of the invention, the reduction of microbial activity ismeasured on site.

In accordance with some variations of this embodiment of the invention,the biocide is capable of killing at least 50% of the microorganisms ina liquid test sample within 3 hours after administration. In accordancewith some variations of this embodiment of the invention, the biocide iscapable of killing at least 50% of the microorganisms in a liquid testsample within 1 hour after administration. In accordance with somevariations of this embodiment of the invention, the biocide is capableof killing at least 50% of the microorganisms in a liquid test samplewithin 30 minutes after administration. In accordance with somevariations of this embodiment of the invention, after the recited timeperiod there is a residual of biocide, expressed as total chlorine, ofat least 0.5 ppm. In accordance with some variations of this embodimentof the invention, after the recited time period there is a residual ofbiocide, expressed as total chlorine, that is too low to be measured.

In accordance with some variations of this embodiment of the invention,the biocide is capable of killing at least 75% of the microorganisms ina liquid test sample within 3 hours after administration. In accordancewith some variations of this embodiment of the invention, the biocide iscapable of killing at least 75% of the microorganisms in a liquid testsample within 1 hour after administration. In accordance with somevariations of this embodiment of the invention, the biocide is capableof killing at least 75% of the microorganisms in a liquid test samplewithin 30 minutes after administration. In accordance with somevariations of this embodiment of the invention, after the recited timeperiod there is a residual of biocide, expressed as total chlorine, ofat least 0.5 ppm. In accordance with some variations of this embodimentof the invention, after the recited time period there is a residual ofbiocide, expressed as total chlorine, that is too low to be measured.

In accordance with some variations of this embodiment of the invention,the biocide is capable of killing at least 90% of the microorganisms ina liquid test sample within 3 hours after administration. In accordancewith some variations of this embodiment of the invention, the biocide iscapable of killing at least 90% of the microorganisms in a liquid testsample within 1 hour after administration. In accordance with somevariations of this embodiment of the invention, the biocide is capableof killing at least 90% of the microorganisms in a liquid test samplewithin 30 minutes after administration. In accordance with somevariations of this embodiment of the invention, after the recited timeperiod there is a residual of biocide, expressed as total chlorine, ofat least 0.5 ppm. In accordance with some variations of this embodimentof the invention, after the recited time period there is a residual ofbiocide, expressed as total chlorine, that is too low to be measured.

There is also provided, in accordance with an embodiment of theinvention, apparatus for applying a biocide to a medium, comprising:

a salt-containing reservoir containing a salt of the formulaY^(x−)[NH₂R³R⁴]⁺ _(x), or a mixture of such salts, wherein

Y^(x−) is a basic form of an acid Y that contains at least one moietyselected from the group consisting of a primary amine moiety, asecondary amine moiety, a tertiary amine moiety, an amide moiety, animide moiety, a sulfamide moiety, a sulfimide moiety, and an amineiminemoiety;

[NH₂R³R⁴]⁺ is an acidic form of a base NHR³R⁴ wherein:

R³ and R⁴ are each independently selected from the group consisting of Hand C₁₋₈ alkyl,

or R³ and R⁴, together with the nitrogen atom to which they areattached, form a 5- to 10-member heterocyclic ring optionallysubstituted by one or more groups selected from C₁₋₆ alkyl, C₃₋₈cycloalkyl, halogen, hydroxy, —OC₁₋₆ alkyl or —OC₃₋₈ cycloalkyl; and

and x is 1 to 3;

a source of hypochlorite oxidant dilution having a concentration of notmore than 24,000 ppm expressed as total chlorine,

and a mixing chamber operable to mix the dilution and the salt ormixture of salts in a molar ratio of [NH₂R³R⁴]⁺ to hypochlorite of atleast 1:1, to produce the biocide in the mixing chamber.

In some variations of this embodiment of the invention, the source ofhypochlorite oxidant dilution has a concentration of not more than12,000 ppm as total chlorine.

In some variations of this embodiment of the invention, Y is selectedfrom the group consisting of straight, branched and cyclic moleculescontaining at least one moiety selected from the group consisting of anamide moiety, an imide moiety, a sulfamide moiety, a sulfimide moiety,and an amineimine moiety, and Y^(x−) is basic form of the molecule. Insome variations of this embodiment of the invention, at least one of theat least one amide moiety, imide moiety, sulfamide moiety, sulfimidemoiety, or amineimine moiety is ionized to the corresponding anionicform.

In some variations of this embodiment of the invention, Y is anamphoteric molecule containing at least one moiety selected from thegroup consisting of COOH and SO₃H and at least one moiety selected fromthe group consisting of a primary amine moiety, a secondary aminemoiety, and a tertiary amine moiety, and Y^(x−) is an anionic form ofthe amphoteric molecule. In some variations of this embodiment of theinvention, at least one of the at least one COOH and SO₃H is ionized tothe corresponding anionic form.

In accordance with some variations of this embodiment of the invention,the salt or mixture of salts is present in the salt-containing reservoiras an aqueous solution.

In accordance with some variations of this embodiment of the invention,the source of hypochlorite oxidant dilution comprises ahypochlorite-containing reservoir containing a hypochlorite oxidantsolution, and a diluter operable to dilute the hypochlorite oxidantsolution to produce the hypochlorite oxidant dilution having aconcentration of not more than 24,000 ppm expressed as total chlorine.In accordance with some variations of this embodiment of the invention,the diluter is operable to dilute the hypochlorite oxidant solution toproduce the hypochlorite oxidant dilution having a concentration of notmore than 12,000 ppm as total chlorine. In accordance with somevariations of this embodiment of the invention, the diluter and themixing chamber are a single conduit which is adapted to dilute thehypochlorite oxidant prior to mixing with the salt or mixture of salts.

In accordance with some variations of this embodiment of the invention,the apparatus further comprising an egress adapted to enable applicationof the biocide from the mixing chamber to the medium.

There is also provided, in accordance with an embodiment of theinvention, a salt of the formula Y^(x−)[NHR³R⁴Cl]⁺ _(x), wherein

Y^(x−) is a basic form of an acid Y that contains at least one moietyselected from the group consisting of a primary amine moiety, asecondary amine moiety, a tertiary amine moiety, an amide moiety, animide moiety, a sulfamide moiety, a sulfimide moiety, and an amineiminemoiety; and

[NHR³R⁴Cl]⁺ is an acidic form of a base NHR³R⁴ wherein:

R³ and R⁴ are each independently selected from the group consisting of Hand C₁₋₈ alkyl,

or R³ and R⁴, together with the nitrogen atom to which they areattached, form a 5- to 10-member heterocyclic ring optionallysubstituted by one or more groups selected from C₁₋₆ alkyl, C₃₋₈cycloalkyl, halogen, hydroxy, —OC₁₋₆ alkyl or —OC₃₋₈ cycloalkyl; and

x is 1 to 3.

In accordance with some variations of this embodiment of the invention,Y is selected from the group consisting of straight, branched and cyclicmolecules containing at least one moiety selected from the groupconsisting of an amide moiety, an imide moiety, a sulfamide moiety, asulfimide moiety, and an amineimine moiety, and Y^(x−) is basic form ofthe molecule. In accordance with some variations of this embodiment ofthe invention, at least one of the at least one amide moiety, imidemoiety, sulfamide moiety, sulfimide moiety, or amineimine moiety isionized to the corresponding anionic form.

In accordance with some variations of this embodiment of the invention,Y is selected from the group consisting of amphoteric moleculescontaining at least one moiety selected from the group consisting of aprimary amine moiety, a secondary amine moiety, and a tertiary aminemoiety, and at least one moiety selected from the group consisting ofCOOH and SO₃H, and Y^(x−) is an anionic form of the amphoteric molecule.In accordance with some variations of this embodiment of the invention,at least one of the at least one COOH and SO₃H is ionized to thecorresponding anionic form.

In accordance with some variations of this embodiment of the invention,Y^(x−) is of the formula [R¹R²N-A-COO]^(x−) or [R¹R²N-A-SO₃]^(x−),wherein:

A is a bond, straight-chain or branched C₁₋₂₀ alkyl, straight-chain orbranched C₂₋₂₀ alkenyl, straight-chain or branched C₂₋₂₀ alkynyl, C₃₋₁₀cycloalkyl, straight-chain or branched C₄-C₂₀ alkylcycloalkyl, C₄₋₁₀cycloalkenyl, C₄₋₁₀ cycloalkynyl, or C₆-C₁₀ aryl, wherein each C₁₋₂₀alkyl, C₂₋₂₀ alkenyl, C₂₋₂₀ alkynyl, C₃₋₁₀ cycloalkyl, C₄-C₂₀alkylcycloalkyl, C₄₋₁₀ cycloalkenyl, C₄₋₁₀ cycloalkynyl or C₆-C₁₀ arylis optionally substituted with one or more groups selected from —COOH,—COH, —SCH₃, —NH₂, ═NH, —NHC(═NH)NH₂, —C(═O)NH₂, —OH, 4-hydroxyphenyl,5-imidazolyl, 3-indolyl, halogen, —SO₃H, ═O, C₁₋₈ alkyl, C₃₋₈cycloalkyl, C₄₋₉ cycloalkylalkyl, phenyl, 4-methylphenyl, benzyl,—O—C₃₋₈ cyclalkyl, —O—C₃₋₈ cycloalkyl, cycloalkylalkyl, —O-phenyl,—O-4-methylphenyl, —O-benzyl, —SO₂R⁷ or —NHR⁷ wherein R⁷ is H, C₁₋₈alkyl, phenyl, 4-methylphenyl, benzyl or —NH₂, and wherein each C₁₋₂₀alkyl, C₂₋₂₀ alkenyl, C₂₋₂₀ alkynyl, C₃₋₁₀ cycloalkyl, C₄-C₂₀alkylcycloalkyl, C₄₋₁₀ cycloalkenyl, C₄₋₁₀ cycloalkynyl or C₆-C₁₀ aryloptionally contains one to three heteroatoms selected from N, O and S;

R¹ and R² are each independently selected from the group consisting ofH, straight-chain or branched C₁₋₂₀ alkyl, straight-chain or branchedC₂₋₂₀ alkenyl, straight-chain or branched C₂₋₂₀ alkynyl, C₃₋₁₀cycloalkyl, straight-chain or branched C₄-C₂₀ alkylcycloalkyl, C₄₋₁₀cycloalkenyl, C₄₋₁₀ cycloalkynyl, or C₆-C₁₀ aryl, wherein each C₁₋₂₀alkyl, C₂₋₂₀ alkenyl, C₂₋₂₀ alkynyl, C₃₋₁₀ cycloalkyl, C₄-C₂₀alkylcycloalkyl, C₄₋₁₀ cycloalkenyl, C₄₋₁₀ cycloalkynyl or C₆-C₁₀ arylis optionally substituted with one or more groups selected from —COOH,—COH, —SCH₃, —NH₂, ═NH, —NHC(═NH)NH₂, —C(═O)NH₂, —OH, 4-hydroxyphenyl,5-imidazolyl, 3-indolyl, halogen, —SO₃H, ═O, C₁₋₈ alkyl, C₃₋₈cycloalkyl, C₄₋₉ cycloalkylalkyl, phenyl, 4-methylphenyl, benzyl,—O—C₃₋₈ cyclalkyl, —O—C₃₋₈ cycloalkyl, —O—C₄₋₉ cycloalkylalkyl,—O-phenyl, —O-4-methylphenyl, —O-benzyl, —SO₂R⁷ or —NHR⁷ wherein R⁷ isH, C₁₋₈ alkyl, phenyl, 4-methylphenyl, benzyl or —NH₂, and wherein eachC₁₋₂₀ alkyl, C₂₋₂₀ alkenyl, C₂₋₂₀ alkynyl, C₃₋₁₀ cycloalkyl, C₄-C₂₀alkylcycloalkyl, C₄₋₁₀ cycloalkenyl, C₄₋₁₀ cycloalkynyl or C₆-C₁₀ aryloptionally contains one to three heteroatoms selected from N, O and S;

or R¹ and A, together with the nitrogen atom to which they are attached,form a 5- to 10-member heterocyclic ring or a 5- to 10-memberheteroaromatic ring in which the free electron pair of the nitrogen atomto which R¹ and A is attached is not part of the aromatic pi-electronsystem, the 5- to 10-member heterocyclic or heteroaromatic ring beingoptionally substituted by one or more groups selected from C₁₋₆ alkyl,C₃₋₈ cycloalkyl, halogen, hydroxy, —OC₁₋₆ alkyl or —OC₃₋₈ cycloalkyl;

or R¹ and R², together with the nitrogen atom to which they areattached, form a 5- to 10-member heterocyclic ring or a 5- to 10-memberheteroaromatic ring in which the free electron pair of the nitrogen atomto which R¹ and A is attached is not part of the aromatic pi-electronsystem, the 5- to 10-member heterocyclic or heteroaromatic ring beingoptionally substituted by one or more groups selected from C₁₋₆ alkyl,C₃₋₈ cycloalkyl, halogen, hydroxy, —OC₁ alkyl or —OC₃₋₈ cycloalkyl.

In accordance with some variations of this embodiment of the invention,Y is selected from the group consisting of carbamic acid, sulfamic acid,glycine, glutamine, arginine, histidine, and lysine.

In accordance with some variations of this embodiment of the invention,Y is selected from the group consisting of melamine, cyanuric acid,hydantoin, dialkyl hydantoin, biuret, succinamide, succinimide,creatine, and creatinine.

There is also provided, in accordance with an embodiment of theinvention, a molecular species selected from the group consisting ofcompounds of the formulae [R¹R²NCl-A-COO]and [R¹R²NCl-A-SO₃] and ions ofthe formulae [R¹NCl-A-COO]⁻ and [R¹NCl-A-SO₃]⁻, and tautomers thereof,wherein A, R¹ and R² are as defined above.

In accordance with some variations of this embodiment of the invention,the molecular species is an N-chlorocarbamate, an N-chlorosulfamate, anN-chloro ammonium carbamate, or an N-chloro ammonium sulfamate.

There is also provided, in accordance with another embodiment of theinvention, a method for controlling microbial or biofilm growth in amedium, the method comprising mixing

a nitrogen-containing compound or mixture of such compounds selectedfrom the group consisting of:

salts of the formula Y^(x−)Z^(n+) _(x/n), wherein x and Y^(x−) are asdefined above, and Z⁺ is a cation other than a cation of the form[NH₂R³R⁴]⁺ as defined above wherein n is a whole number greater thanzero; and

amphoteric molecules Q containing at least one moiety selected from thegroup consisting of COOH and SO₃H and at least one moiety selected fromthe group consisting of a primary amine moiety, a secondary aminemoiety, and a tertiary amine moiety;

and an aqueous solution of a hypochlorite oxidant to form a biocide,

wherein the molar ratio of nitrogen atoms in the nitrogen-containingcompound to the hypochlorite is at least 1:1,

and applying the biocide to the medium.

In accordance with some variations of this embodiment of the invention,Y is selected from the group consisting of straight, branched and cyclicmolecules containing at least one moiety selected from the groupconsisting of an amide moiety, an imide moiety, a sulfamide moiety, asulfimide moiety, and an amineimine moiety, and Y^(x−) is a basic formof the molecule. In some variations of this embodiment of the invention,in Y^(x−) at least one of the at least one amide moiety, imide moiety,sulfamide moiety, sulfimide moiety, or amineimine moiety is ionized tothe corresponding anionic form.

In accordance with some variations of this embodiment of the invention,Y is selected from the group consisting of amphoteric moleculescontaining at least one moiety selected from the group consisting ofCOOH and SO₃H and at least one moiety selected from the group consistingof a primary amine moiety, a secondary amine moiety, and a tertiaryamine moiety, and Y^(x−) is an anionic form of the amphoteric molecule.In some variations of this embodiment of the invention, at least one ofthe at least one COOH and SO₃H is ionized to the corresponding anionicform.

In accordance with some variations of this embodiment of the invention,Y^(x−) is of the formula [R¹R²N-A-COO]^(x−) or [R¹R²N-A-SO₃]^(x−),wherein:

A is a bond, straight-chain or branched C₁₋₂₀ alkyl, straight-chain orbranched C₂₋₂₀ alkenyl, straight-chain or branched C₂₋₂₀ alkynyl, C₃₋₁₀cycloalkyl, straight-chain or branched C₄-C₂₀ alkylcycloalkyl, C₄₋₁₀cycloalkenyl, C₄₋₁₀ cycloalkynyl, or C₆-C₁₀ aryl, wherein each C₁₋₂₀alkyl, C₂₋₂₀ alkenyl, C₂₋₂₀ alkynyl, C₃₋₁₀ cycloalkyl, C₄-C₂₀alkylcycloalkyl, C₄₋₁₀ cycloalkenyl, C₄₋₁₀ cycloalkynyl or C₆-C₁₀ arylis optionally substituted with one or more groups selected from —COOH,—COH, —SCH₃, —NH₂, ═NH, —NHC(═NH)NH₂, —C(═O)NH₂, —OH, 4-hydroxyphenyl,5-imidazolyl, 3-indolyl, halogen, —SO₃H, ═O, C₁₋₈ alkyl, C₃₋₈cycloalkyl, C₄₋₉ cycloalkylalkyl, phenyl, 4-methylphenyl, benzyl,—O—C₃₋₈ cyclalkyl, —O—C₃₋₈ cycloalkyl, —O—C₄₋₉ cycloalkylalkyl,—O-phenyl, —O-4-methylphenyl, —O-benzyl, —SO₂R⁷ or —NHR⁷ wherein R⁷ isH, C₁₋₈ alkyl, phenyl, 4-methylphenyl, benzyl or —NH₂, and wherein eachC₁₋₂₀ alkyl, C₂₋₂₀ alkenyl, C₂₋₂₀ alkynyl, C₃₋₁₀ cycloalkyl, C₄-C₂₀alkylcycloalkyl, C₄₋₁₀ cycloalkenyl, C₄₋₁₀ cycloalkynyl or C₆-C₁₀ aryloptionally contains one to three heteroatoms selected from N, O and S;

R¹ and R² are each independently selected from the group consisting ofH, straight-chain or branched C₁₋₂₀ alkyl, straight-chain or branchedC₂₋₂₀ alkenyl, straight-chain or branched C₂₋₂₀ alkynyl, C₃₋₁₀cycloalkyl, straight-chain or branched C₄-C₂₀ alkylcycloalkyl, C₄₋₁₀cycloalkenyl, C₄₋₁₀ cycloalkynyl, or C₆-C₁₀ aryl, wherein each C₁₋₂₀alkyl, C₂₋₂₀ alkenyl, C₂₋₂₀ alkynyl, C₃₋₁₀ cycloalkyl, C₄-C₂₀alkylcycloalkyl, C₄₋₁₀ cycloalkenyl, C₄₋₁₀ cycloalkynyl or C₅-C₁₀ arylis optionally substituted with one or more groups selected from —COOH,—COH, —SCH₃, —NH₂, ═NH, —NHC(═NH)NH₂, —C(═O)NH₂, —OH, 4-hydroxyphenyl,5-imidazolyl, 3-indolyl, halogen, —SO₃H, ═O, C₁₋₈ alkyl, C₃₋₈cycloalkyl, C₄₋₉ cycloalkylalkyl, phenyl, 4-methylphenyl, benzyl,—O—C₃₋₈ cyclalkyl, —O—C₃₋₈ cycloalkyl, —O—C₄₋₉ cycloalkylalkyl,—O-phenyl, —O-4-methylphenyl, —O-benzyl, —SO₂R⁷ or —NHR⁷ wherein R⁷ isH, C₁₋₈ alkyl, phenyl, 4-methylphenyl, benzyl or —NH₂, and wherein eachC₁₋₂₀ alkyl, C₂₋₂₀ alkenyl, C₂₋₂₀ alkynyl, C₃₋₁₀ cycloalkyl, C₄-C₂₀alkylcycloalkyl, C₄₋₁₀ cycloalkenyl, C₄₋₁₀ cycloalkynyl or C₆-C₁₀ aryloptionally contains one to three heteroatoms selected from N, O and S;

or R¹ and A, together with the nitrogen atom to which they are attached,form a 5- to 10-member heterocyclic ring or a 5- to 10-memberheteroaromatic ring in which the free electron pair of the nitrogen atomto which R¹ and A is attached is not part of the aromatic pi-electronsystem, the 5- to 10-member heterocyclic or heteroaromatic ring beingoptionally substituted by one or more groups selected from C₁₋₆ alkyl,C₃₋₈ cycloalkyl, halogen, hydroxy, —OC₁₋₆ alkyl or —OC₃₋₈ cycloalkyl;

or R¹ and R², together with the nitrogen atom to which they areattached, form a 5- to 10-member heterocyclic ring or a 5- to 10-memberheteroaromatic ring in which the free electron pair of the nitrogen atomto which R¹ and A is attached is not part of the aromatic pi-electronsystem, the 5- to 10-member heterocyclic or heteroaromatic ring beingoptionally substituted by one or more groups selected from C₁₋₆ alkyl,C₃₋₈ cycloalkyl, halogen, hydroxy, —OC₁₋₆ alkyl or —OC₃₋₈ cycloalkyl.

In accordance with some variations of this embodiment of the invention,Q is of the formula R¹R²N-A-COOH or R¹R²N-A-SO₃H, wherein:

A is a bond, straight-chain or branched C₁₋₂₀ alkyl, straight-chain orbranched C₂₋₂₀ alkenyl, straight-chain or branched C₂₋₂₀ alkynyl, C₃₋₁₀cycloalkyl, straight-chain or branched C₄-C₂₀ alkylcycloalkyl, C₄₋₁₀cycloalkenyl, C₄₋₁₀ cycloalkynyl, or C₆-C₁₀ aryl, wherein each C₁₋₂₀alkyl, C₂₋₂₀ alkenyl, C₂₋₂₀ alkynyl, C₃₋₁₀ cycloalkyl, C₄-C₂₀alkylcycloalkyl, C₄₋₁₀ cycloalkenyl, C₄₋₁₀ cycloalkynyl or C₆-C₁₀ arylis optionally substituted with one or more groups selected from —COOH,—COH, —SCH₃, —NH₂, ═NH, —NHC(═NH)NH₂, —C(═O)NH₂, —OH, 4-hydroxyphenyl,5-imidazolyl, 3-indolyl, halogen, —SO₃H, ═O, C₁₋₈ alkyl, C₃₋₈cycloalkyl, C₄₋₉ cycloalkylalkyl, phenyl, 4-methylphenyl, benzyl,—O—C₃₋₈ cyclalkyl, —O—C₃₋₈ cycloalkyl, —O—C₄₋₉ cycloalkylalkyl,—O-phenyl, —O-4-methylphenyl, —O-benzyl, —SO₂R⁷ or —NHR⁷ wherein R⁷ isH, C₁₋₈ alkyl, phenyl, 4-methylphenyl, benzyl or —NH₂, and wherein eachC₁₋₂₀ alkyl, C₂₋₂₀ alkenyl, C₂₋₂₀ alkynyl, C₃₋₁₀ cycloalkyl, C₄-C₂₀alkylcycloalkyl, C₄₋₁₀ cycloalkenyl, C₄₋₁₀ cycloalkynyl or C₆-C₁₀ aryloptionally contains one to three heteroatoms selected from N, O and S;

R¹ and R² are each independently selected from the group consisting ofH, straight-chain or branched C₁₋₂₀ alkyl, straight-chain or branchedC₂₋₂₀ alkenyl, straight-chain or branched C₂₋₂₀ alkynyl, C₃₋₁₀cycloalkyl, straight-chain or branched C₄-C₂₀ alkylcycloalkyl, C₄₋₁₀cycloalkenyl, C₄₋₁₀ cycloalkynyl, or C₆-C₁₀ aryl, wherein each C₁₋₂₀alkyl, C₂₋₂₀ alkenyl, C₂₋₂₀ alkynyl, C₃₋₁₀ cycloalkyl, C₄-C₂₀alkylcycloalkyl, C₄₋₁₀ cycloalkenyl, C₄₋₁₀ cycloalkynyl or C₆-C₁₀ arylis optionally substituted with one or more groups selected from —COOH,—COH, —SCH₃, —NH₂, ═NH, —NHC(═NH)NH₂, —C(═O)NH₂, —OH, 4-hydroxyphenyl,5-imidazolyl, 3-indolyl, halogen, —SO₃H, ═O, C₁₋₈ alkyl, C₃₋₈cycloalkyl, C₄₋₉ cycloalkylalkyl, phenyl, 4-methylphenyl, benzyl,—O—C₃₋₈ cyclalkyl, —O—C₃₋₈ cycloalkyl, —O—C₄₋₉ cycloalkylalkyl,—O-phenyl, —O-4-methylphenyl, —O-benzyl, —SO₂R⁷ or —NHR⁷ wherein R⁷ isH, C₁₋₈ alkyl, phenyl, 4-methylphenyl, benzyl or —NH₂, and wherein eachC₁₋₂₀ alkyl, C₂₋₂₀ alkenyl, C₂₋₂₀ alkynyl, C₃₋₁₀ cycloalkyl, C₄-C₂₀alkylcycloalkyl, C₄₋₁₀ cycloalkenyl, C₄₋₁₀ cycloalkynyl or C₆-C₁₀ aryloptionally contains one to three heteroatoms selected from N, O and S;

or R¹ and A, together with the nitrogen atom to which they are attached,form a 5- to 10-member heterocyclic ring or a 5- to 10-memberheteroaromatic ring in which the free electron pair of the nitrogen atomto which R¹ and A is attached is not part of the aromatic pi-electronsystem, the 5- to 10-member heterocyclic or heteroaromatic ring beingoptionally substituted by one or more groups selected from C₁₋₆ alkyl,C₃₋₈ cycloalkyl, halogen, hydroxy, —OC₁₋₆ alkyl or —OC₃₋₈ cycloalkyl;

or R¹ and R², together with the nitrogen atom to which they areattached, form a 5- to 10-member heterocyclic ring or a 5- to 10-memberheteroaromatic ring in which the free electron pair of the nitrogen atomto which R¹ and A is attached is not part of the aromatic pi-electronsystem, the 5- to 10-member heterocyclic or heteroaromatic ring beingoptionally substituted by one or more groups selected from C₁₋₆ alkyl,C₃₋₈ cycloalkyl, halogen, hydroxy, —OC₁₋₆ alkyl or —OC₃₋₈ cycloalkyl;

or a salt thereof.

In accordance with some variations of this embodiment of the invention,the nitrogen-containing compound is salt of creatinine, cyanuric acid,melamine, or dialkylhydantoin.

In accordance with some variations of this embodiment of the invention,the concentration of the hypochlorite oxidant in the aqueoushypochlorite oxidant solution immediately prior to mixing with thenitrogen-containing compound is not more than 24,000 ppm as totalchlorine. In accordance with some variations of this embodiment of theinvention, the concentration of the hypochlorite oxidant in the aqueoushypochlorite oxidant solution immediately prior to mixing with thenitrogen-containing compound is not more than 12,000 ppm as totalchlorine.

In accordance with some variations of this embodiment of the invention,the nitrogen-containing compound or mixture thereof is in an aqueoussolution at a concentration of 0.5-60% w/v prior to mixing with thehypochlorite oxidant solution.

In accordance with some variations of this embodiment of the invention,the mixing takes place in a mixing chamber into and out of which thereis a continuous flow of water during the mixing.

In accordance with some variations of this embodiment of the invention,the biocide is applied to the medium substantially as the biocide isformed. In accordance with other variations of this embodiment of theinvention, the biocide is applied to the medium within 30 seconds offormation of the biocide. In accordance with other variations of thisembodiment of the invention, the biocide is applied to the medium within60 seconds of formation of the biocide. In accordance with othervariations of this embodiment of the invention, the biocide is appliedto the medium within 90 seconds of formation of the biocide. Inaccordance with other variations of this embodiment of the invention,the biocide is applied to the medium within 120 seconds of formation ofthe biocide. In accordance with other variations of this embodiment ofthe invention, the biocide is applied to the medium within 150 secondsof formation of the biocide. In accordance with other variations of thisembodiment of the invention, the biocide is applied to the medium within180 seconds of formation of the biocide.

In accordance with some variations of this embodiment of the invention,the mixing chamber is a conduit.

In accordance with other variations of this embodiment of the invention,the mixing takes place in a mixing chamber out of which there is not acontinuous flow of water during the mixing. In accordance with othervariations of this embodiment of the invention, biocide is applied tothe medium substantially immediately upon completion of the mixing. Inaccordance with other variations of this embodiment of the invention,the biocide is applied to the medium within 30 seconds of completion ofthe mixing. In accordance with other variations of this embodiment ofthe invention, the biocide is applied to the medium within 60 seconds ofcompletion of the mixing. In accordance with other variations of thisembodiment of the invention, the biocide is applied to the medium within90 seconds of completion of the mixing. In accordance with othervariations of this embodiment of the invention, the biocide is appliedto the medium within 120 seconds of completion of the mixing. Inaccordance with other variations of this embodiment of the invention,the biocide is applied to the medium within 150 seconds of completion ofthe mixing. In accordance with other variations of this embodiment ofthe invention, the biocide is applied to the medium within 180 secondsof completion of the mixing.

In accordance with some variations of this embodiment of the invention,the hypochlorite oxidant is selected from the group consisting ofalkaline and alkali earth metal hypochlorites, hypochlorite released towater from a stable chlorine carrier and hypochlorite formed in situfrom chlorine gas, and mixtures thereof. In accordance with somevariations of this embodiment of the invention, the stable chlorinecarrier is selected from the group consisting of trichlorocyanuric acid,dichlorodimethylhydantoin and monochlorodimethylhydantoin. In accordancewith some variations of this embodiment of the invention, thehypochlorite oxidant is selected from the group consisting of lithiumhypochlorite, sodium hypochlorite, calcium hypochlorite, magnesiumhypochlorite and potassium hypochlorite. In accordance with somevariations of this embodiment of the invention, the hypochlorite oxidantis sodium hypochlorite.

In accordance with some variations of this embodiment of the invention,the nitrogen-containing compound is selected from the group consistingof carbamic acid, sulfamic acid, glycine, glutamine, arginine,histidine, lysine, and mixtures thereof.

In accordance with some variations of this embodiment of the invention,Y is selected from the group consisting of carbamic acid, sulfamic acid,glycine, glutamine, arginine, histidine, and lysine.

In accordance with some variations of this embodiment of the invention,the molar ratio of nitrogen atoms in the nitrogen-containing compound ormixture thereof to the hypochlorite oxidant is 1:1. In accordance withsome variations of this embodiment of the invention, the molar ratio ofthe nitrogen-containing compound to the hypochlorite oxidant is 1:1. Inaccordance with some variations of this embodiment of the invention, themolar ratio of nitrogen atoms in the nitrogen-containing compound ormixture thereof to the hypochlorite oxidant is greater than 1:1. Inaccordance with other variations of this embodiment of the invention,the molar ratio of the nitrogen-containing compound to the hypochloriteoxidant is greater than 1:1.

In accordance with some variations of this embodiment of the invention,the concentration of the hypochlorite oxidant in the aqueoushypochlorite oxidant solution prior to mixing with thenitrogen-containing compound is not more than 24,000 ppm as totalchlorine, and the mixing chamber comprises a conduit through which waterflows as the hypochlorite oxidant solution and the nitrogen-containingcompound are mixed. In accordance with some variations of thisembodiment of the invention, the concentration of the hypochloriteoxidant in the aqueous hypochlorite oxidant solution immediately priorto mixing with the nitrogen-containing compound is not more than 12,000ppm as total chlorine. In accordance with some variations of thisembodiment of the invention, the solution of hypochlorite oxidant isprepared in situ in the conduit prior to addition of the solution of thenitrogen-containing compound to the conduit.

In accordance with some variations of this embodiment of the invention,the nitrogen-containing compound is diluted prior to mixing with thehypochlorite oxidant.

In accordance with some variations of this embodiment of the invention,the biocide has a pH of between 8.0 and 11.5 immediately prior to beingapplied to the medium. In accordance with some variations of thisembodiment of the invention, the biocide has a pH of at least 8.5immediately prior to being applied to the medium. In accordance withsome variations of this embodiment of the invention, the biocide has apH of at least 9.0 immediately prior to being applied to the medium. Inaccordance with some variations of this embodiment of the invention, thebiocide has a pH of at least 9.5 immediately prior to being applied tothe medium. In accordance with some variations of this embodiment of theinvention, the biocide has a pH of at least 10.0 immediately prior tobeing applied to the medium. In accordance with some variations of thisembodiment of the invention, the biocide has a pH of at least 10.5immediately prior to being applied to the medium. In accordance withsome variations of this embodiment of the invention, the biocide has apH of at least 11.0 immediately prior to being applied to the medium. Inaccordance with some variations of this embodiment of the invention, thebiocide has a pH of no more than 11.5 immediately prior to being appliedto the medium.

In accordance with some variations of this embodiment of the invention,the medium is selected from the group consisting of pulp and paperfactory water, cooling tower water, waste water, reclaimed waste water,clay slurries, starch slurries, sludge, soil, colloidal suspension, andirrigation water. In accordance with some variations of this embodimentof the invention, the medium is pulp and paper factory process water. Inaccordance with some variations of this embodiment of the invention, themedium is cooling tower water. In accordance with some variations ofthis embodiment of the invention, the medium is waste water. Inaccordance with some variations of this embodiment of the invention, themedium is reclaimed waste water. In accordance with some variations ofthis embodiment of the invention, the medium is a clay slurry. Inaccordance with some variations of this embodiment of the invention, themedium is a starch slurry. In accordance with some variations of thisembodiment of the invention, the medium is a sludge. In accordance withsome variations of this embodiment of the invention, the medium is soil.In accordance with some variations of this embodiment of the invention,the medium is a colloidal suspension. In accordance with some variationsof this embodiment of the invention, the medium is irrigation water. Inaccordance with some variations of this embodiment of the invention, themedium is a medium containing strong reducing agents or having a highreducing capacity, viz. an ORP of not greater than 150 millivolts.

In accordance with some variations of this embodiment of the invention,the hypochlorite oxidant and the nitrogen-containing compound are mixedin the absence of added bromide and the medium is substantially free ofadded bromide during application of the biocide. In accordance with somevariations of this embodiment of the invention, bromide is not added tothe medium as a component to supplement or enhance the biocide.

In accordance with some variations of this embodiment of the invention,the biocide is applied to the medium periodically with a duty cycle ofless than 1:2. In accordance with some variations of this embodiment ofthe invention, the biocide is applied to the medium periodically with aduty cycle of between about 1:5 and 1:10. In accordance with somevariations of this embodiment of the invention, the biocide is appliedto the medium periodically with a duty cycle of less than 1:10. Inaccordance with some variations of this embodiment of the invention, thebiocide is applied to the medium periodically with a duty cycle of lessthan 1:25. In accordance with some variations of this embodiment of theinvention, the biocide is applied to the medium periodically with a dutycycle of less than 1:50.

In accordance with some variations of this embodiment of the invention,the biocide is applied to the medium at a rate to maintain in thebiocide a stable pH of at least 8.0 as the biocide is produced.

In accordance with some variations of this embodiment of the invention,the concentration of the biocide immediately prior to being applied tothe medium is from 1000 to 12,000 ppm expressed as total chlorine.

In accordance with some variations of this embodiment of the invention,the medium has a pH of between about 5 and about 11.5 before the biocideis applied to the medium. In accordance with some variations of thisembodiment of the invention, the medium has a pH of between about 6 andabout 10 before the biocide is applied to the medium. In accordance withsome variations of this embodiment of the invention, the medium has a pHof between about 7 and about 9 before the biocide is applied to themedium.

In accordance with some variations of this embodiment of the invention,the concentration of the biocide in the medium, upon application of thebiocide to the medium, is 0.5-300 ppm expressed as chlorine. Inaccordance with some variations of this embodiment of the invention, theconcentration of the biocide in the medium, upon application of thebiocide to the medium, is 1-10 ppm expressed as chlorine.

In accordance with some variations of this embodiment of the invention,the biocide is effective within 24 hours of application to the medium.In accordance with some variations of this embodiment of the invention,the biocide is effective within 1 hour of application to the medium. Inaccordance with some variations of this embodiment of the invention, thebiocide is effective within 20 minutes of application to the medium. Inaccordance with some variations of this embodiment of the invention, thebiocide is effective within 15 minutes of application to the medium.

In accordance with some variations of this embodiment of the invention,the biocide is capable of reducing microbial activity by at least 50%within 3 hours after administration. In accordance with some variationsof this embodiment of the invention, the biocide is capable of reducingmicrobial activity by at least 50% within 1 hour after administration.In accordance with some variations of this embodiment of the invention,the biocide is capable of reducing microbial activity by at least 50%within 30 minutes after administration. In the context of thesevariations of this embodiment of the invention, reduction in microbialactivity may be correlated to an increase in operational efficiency ofthe system being treated. For example, in a paper machine, a reductionin microbial activity will result in improved runnability of the papermachine. In some contexts, reduced microbial activity can be correlatedto decreased production of ATP or to decreased production of catalase.In accordance with some variations of this embodiment of the invention,after the recited time period there is a residual of biocide, expressedas total chlorine, of at least 0.5 ppm. In accordance with somevariations of this embodiment of the invention, after the recited timeperiod there is a residual of biocide, expressed as total chlorine, thatis too low to be measured. In accordance with some variations of thisembodiment of the invention, the reduction of microbial activity ismeasured in a test sample. In accordance with some variations of thisembodiment of the invention, the reduction of microbial activity ismeasured on site.

In accordance with some variations of this embodiment of the invention,the biocide is capable of reducing microbial activity by at least 75%within 3 hours after administration. In accordance with some variationsof this embodiment of the invention, the biocide is capable of reducingmicrobial activity by at least 75% within 1 hour after administration.In accordance with some variations of this embodiment of the invention,the biocide is capable of reducing microbial activity by at least 75%within 30 minutes after administration. In the context of thesevariations of this embodiment of the invention, reduction in microbialactivity may be correlated to an increase in operational efficiency ofthe system being treated. For example, in a paper machine, a reductionin microbial activity will result in improved runnability of the papermachine. In some contexts, reduced microbial activity can be correlatedto decreased production of ATP or to decreased production of catalase.In accordance with some variations of this embodiment of the invention,after the recited time period there is a residual of biocide, expressedas total chlorine, of at least 0.5 ppm. In accordance with somevariations of this embodiment of the invention, after the recited timeperiod there is a residual of biocide, expressed as total chlorine, thatis too low to be measured. In accordance with some variations of thisembodiment of the invention, the reduction of microbial activity ismeasured in a test sample. In accordance with some variations of thisembodiment of the invention, the reduction of microbial activity ismeasured on site.

In accordance with some variations of this embodiment of the invention,the biocide is capable of reducing microbial activity by at least 90%within 3 hours after administration. In accordance with some variationsof this embodiment of the invention, the biocide is capable of reducingmicrobial activity by at least 90% within 1 hour after administration.In accordance with some variations of this embodiment of the invention,the biocide is capable of reducing microbial activity by at least 90%within 30 minutes after administration. In the context of thesevariations of this embodiment of the invention, reduction in microbialactivity may be correlated to an increase in operational efficiency ofthe system being treated. For example, in a paper machine, a reductionin microbial activity will result in improved runnability of the papermachine. In some contexts, reduced microbial activity can be correlatedto decreased production of ATP or to decreased production of catalase.In accordance with some variations of this embodiment of the invention,after the recited time period there is a residual of biocide, expressedas total chlorine, of at least 0.5 ppm. In accordance with somevariations of this embodiment of the invention, after the recited timeperiod there is a residual of biocide, expressed as total chlorine, thatis too low to be measured. In accordance with some variations of thisembodiment of the invention, the reduction of microbial activity ismeasured in a test sample. In accordance with some variations of thisembodiment of the invention, the reduction of microbial activity ismeasured on site.

In accordance with some variations of this embodiment of the invention,the biocide is capable of killing at least 50% of the microorganisms ina liquid test sample within 3 hours after administration. In accordancewith some variations of this embodiment of the invention, the biocide iscapable of killing at least 50% of the microorganisms in a liquid testsample within 1 hour after administration. In accordance with somevariations of this embodiment of the invention, the biocide is capableof killing at least 50% of the microorganisms in a liquid test samplewithin 30 minutes after administration. In accordance with somevariations of this embodiment of the invention, after the recited timeperiod there is a residual of biocide, expressed as total chlorine, ofat least 0.5 ppm. In accordance with some variations of this embodimentof the invention, after the recited time period there is a residual ofbiocide, expressed as total chlorine, that is too low to be measured.

In accordance with some variations of this embodiment of the invention,the biocide is capable of killing at least 75% of the microorganisms ina liquid test sample within 3 hours after administration. In accordancewith some variations of this embodiment of the invention, the biocide iscapable of killing at least 75% of the microorganisms in a liquid testsample within 1 hour after administration. In accordance with somevariations of this embodiment of the invention, the biocide is capableof killing at least 75% of the microorganisms in a liquid test samplewithin 30 minutes after administration. In accordance with somevariations of this embodiment of the invention, after the recited timeperiod there is a residual of biocide, expressed as total chlorine, ofat least 0.5 ppm. In accordance with some variations of this embodimentof the invention, after the recited time period there is a residual ofbiocide, expressed as total chlorine, that is too low to be measured.

In accordance with some variations of this embodiment of the invention,the biocide is capable of killing at least 90% of the microorganisms ina liquid test sample within 3 hours after administration. In accordancewith some variations of this embodiment of the invention, the biocide iscapable of killing at least 90% of the microorganisms in a liquid testsample within 1 hour after administration. In accordance with somevariations of this embodiment of the invention, the biocide is capableof killing at least 90% of the microorganisms in a liquid test samplewithin 30 minutes after administration. In accordance with somevariations of this embodiment of the invention, after the recited timeperiod there is a residual of biocide, expressed as total chlorine, ofat least 0.5 ppm. In accordance with some variations of this embodimentof the invention, after the recited time period there is a residual ofbiocide, expressed as total chlorine, that is too low to be measured.

In accordance with some variations of this embodiment of the invention,the medium is present in a system from which a portion of the medium isdischarged and replaced during the regular course of operation of thesystem. In accordance with some variations of this embodiment of theinvention, the portion of the medium which is discharged and replacedduring the regular course of operation of the system is continuouslydischarged and replaced during the regular course of operation of thesystem. In accordance with some variations of this embodiment of theinvention, the portion of the medium which is discharged and replacedduring the regular course of operation of the system is discharged andreplaced at least once every 24 hours during the regular course ofoperation of the system.

There is also provided, in accordance with an embodiment of theinvention, an apparatus for applying a biocide to a medium, comprising:

a nitrogen-containing compound reservoir containing anitrogen-containing compound or mixture thereof selected from the groupconsisting of:

salts of the formula Y^(x−)Z^(n+) _(x/n), wherein x and Y^(x−) are asdefined above, Z⁺ is a cation other than a cation of the form [NH₂R³R⁴]⁺as defined above, and n is a whole number greater than zero; and

amphoteric molecules Q containing at least one moiety selected from thegroup consisting of COOH and SO₃H and at least one moiety selected fromthe group consisting of a primary amine moiety, a secondary aminemoiety, and a tertiary amine moiety;

a source of hypochlorite oxidant dilution having a concentration ofbetween not more than 24,000 ppm as total chlorine,

and a mixing chamber operable to mix the dilution and thenitrogen-containing compound or mixture thereof in a molar ratio ofnitrogen atoms in the nitrogen-containing compound to the hypochloriteof at least 1:1, to produce the biocide in the mixing chamber.

In some variations of this embodiment of the invention, the source ofhypochlorite oxidant dilution has a concentration of not more than12,000 ppm as total chlorine.

In some variations of this embodiment of the invention, Y is selectedfrom the group consisting of straight, branched and cyclic moleculescontaining at least one moiety selected from the group consisting of anamide moiety, an imide moiety, a sulfamide moiety, a sulfimide moiety,and an amineimine moiety, and Y^(x−) is basic form of the molecule. Insome variations of this embodiment of the invention, at least one of theat least one amide moiety, imide moiety, sulfamide moiety, sulfimidemoiety, or amineimine moiety is ionized to the corresponding anionicform.

In some variations of this embodiment of the invention, Y is anamphoteric molecule containing at least one moiety selected from thegroup consisting of COOH and SO₃H and at least one moiety selected fromthe group consisting of a primary amine moiety, a secondary aminemoiety, and a tertiary amine moiety, and Y^(x−) is an anionic form ofthe amphoteric molecule. In some variations of this embodiment of theinvention, at least one of the at least one COOH and SO₃H is ionized tothe corresponding anionic form.

In some variations of this embodiment of the invention, Q is anamphoteric molecule containing at least one moiety selected from thegroup consisting of COOH and SO₃H and at least one moiety selected fromthe group consisting of a primary amine moiety, a secondary aminemoiety, and a tertiary amine moiety, and Y^(x−) is an anionic form ofthe amphoteric molecule.

In accordance with some variations of this embodiment of the invention,the source of hypochlorite oxidant dilution comprises ahypochlorite-containing reservoir containing a hypochlorite oxidantsolution, and a diluter operable to dilute the hypochlorite oxidantsolution to produce the hypochlorite oxidant dilution having aconcentration of not more than 24,000 ppm expressed as total chlorine.In accordance with some variations of this embodiment of the invention,the diluter is operable to dilute the hypochlorite oxidant solution toproduce the hypochlorite oxidant dilution having a concentration of notmore than 12,000 ppm as total chlorine. In accordance with somevariations of this embodiment of the invention, the diluter and themixing chamber are a single conduit which is adapted to dilute thehypochlorite oxidant prior to mixing with the salt or mixture of salts.

In accordance with some variations of this embodiment of the invention,the nitrogen-containing compound is present in nitrogen-compoundcontaining reservoir as an aqueous solution.

In accordance with some variations of this embodiment of the invention,the molar ratio of nitrogen atoms in the nitrogen-containing compound ormixture thereof to the hypochlorite oxidant is 1:1. In accordance withsome variations of this embodiment of the invention, the molar ratio ofthe nitrogen-containing compound to the hypochlorite oxidant is 1:1. Inaccordance with some variations of this embodiment of the invention, themolar ratio of nitrogen atoms in the nitrogen-containing compound ormixture thereof to the hypochlorite oxidant is greater than 1:1. Inaccordance with other variations of this embodiment of the invention,the molar ratio of the nitrogen-containing compound to the hypochloriteoxidant is greater than 1:1.

In accordance with some variations of this embodiment of the invention,the apparatus further comprising an egress adapted to enable applicationof the biocide from the mixing chamber to the medium.

There is also provided, in accordance with an embodiment of theinvention, a method for controlling microbial or biofilm growth in amedium, the method comprising mixing a nitrogen-containing compound, abromide and an aqueous solution of a hypochlorite oxidant to form abiocide,

the nitrogen-containing compound being selected from the groupconsisting of salts of the formula Y^(x−)[NH₂R³R⁴]⁺ _(x), salts of theformula Y^(x−)Z^(n+) _(x/n), and molecules Y per se, wherein

-   -   Z and n are as defined above,

Y^(x−) is a basic form of an acid Y that contains at least one moietyselected from the group consisting of a primary amine moiety, asecondary amine moiety, a tertiary amine moiety, an amide moiety, animide moiety, a sulfamide moiety, a sulfimide moiety, and an amineiminemoiety; and

[NH₂R³R⁴]⁺ is an acidic form of a base NHR³R⁴ wherein:

R³ and R⁴ are each independently selected from the group consisting of Hand C₁₋₈ alkyl,

or R³ and R⁴, together with the nitrogen atom to which they areattached, form a 5- to 10-member heterocyclic ring optionallysubstituted by one or more groups selected from C₁₋₆ alkyl, C₃₋₈cycloalkyl, halogen, hydroxy, —OC₁₋₆ alkyl or —OC₃₋₈ cycloalkyl; and

x is 1 to 3;

and the molar ratio of nitrogen atoms in the nitrogen-containingcompound to hypochlorite is at least 1:1,

and applying the biocide to the medium.

In accordance with some variations of this embodiment of the invention,Y is selected from the group consisting of straight, branched and cyclicmolecules containing at least one moiety selected from the groupconsisting of an amide moiety, an imide moiety, a sulfamide moiety, asulfimide moiety, and an amineimine moiety, and Y^(x−) is a basic formof the molecule. In some variations of this embodiment of the invention,in Y^(x−) at least one of the at least one amide moiety, imide moiety,sulfamide moiety, sulfimide moiety, or amineimine moiety is ionized tothe corresponding anionic form.

In accordance with some variations of this embodiment of the invention,Y is selected from the group consisting of amphoteric moleculescontaining at least one moiety selected from the group consisting ofCOOH and SO₃H and at least one moiety selected from the group consistingof a primary amine moiety, a secondary amine moiety, and a tertiaryamine moiety, and Y^(x−) is an anionic form of the amphoteric molecule.In some variations of this embodiment of the invention, at least one ofthe at least one COOH and SO₃H is ionized to the corresponding anionicform.

In accordance with some variations of this embodiment of the invention,Y^(x−) is of the formula [R¹R²N-A-COO]^(x−) or [R¹R²N-A-SO₃]^(x−),wherein:

A is a bond, straight-chain or branched C₁₋₂₀ alkyl, straight-chain orbranched C₂₋₂₀ alkenyl, straight-chain or branched C₂₋₂₀ alkynyl, C₃₋₁₀cycloalkyl, straight-chain or branched C₄-C₂₀ alkylcycloalkyl, C₄₋₁₀cycloalkenyl, C₄₋₁₀ cycloalkynyl, or C₆-C₁₀ aryl, wherein each C₁₋₂₀alkyl, C₂₋₂₀ alkenyl, C₂₋₂₀ alkynyl, C₃₋₁₀ cycloalkyl, C₄-C₂₀alkylcycloalkyl, C₄₋₁₀ cycloalkenyl, C₄₋₁₀ cycloalkynyl or C₆-C₁₀ arylis optionally substituted with one or more groups selected from —COOH,—COH, —SCH₃, —NH₂, ═NH, —NHC(═NH)NH₂, —C(═O)NH₂, —OH, 4-hydroxyphenyl,5-imidazolyl, 3-indolyl, halogen, —SO₃H, ═O, C₁₋₈ alkyl, C₃₋₈cycloalkyl, C₄₋₉ cycloalkylalkyl, phenyl, 4-methylphenyl, benzyl,—O—C₃₋₈ cyclalkyl, —O—C₃₋₈ cycloalkyl, —O—C₄₋₉ cycloalkylalkyl,—O-phenyl, —O-4-methylphenyl, —O-benzyl, —SO₂R⁷ or —NHR⁷ wherein R⁷ isH, C₁₋₈ alkyl, phenyl, 4-methylphenyl, benzyl or —NH₂, and wherein eachC₁₋₂₀ alkyl, C₂₋₂₀ alkenyl, C₂₋₂₀ alkynyl, C₃₋₁₀ cycloalkyl, C₄-C₂₀alkylcycloalkyl, C₄₋₁₀ cycloalkenyl, C₄₋₁₀ cycloalkynyl or C₆-C₁₀ aryloptionally contains one to three heteroatoms selected from N, O and S;

R¹ and R² are each independently selected from the group consisting ofH, straight-chain or branched C₁₋₂₀ alkyl, straight-chain or branchedC₂₋₂₀ alkenyl, straight-chain or branched C₂₋₂₀ alkynyl, C₃₋₁₀cycloalkyl, straight-chain or branched C₄-C₂₀ alkylcycloalkyl, C₄₋₁₀cycloalkenyl, C₄₋₁₀ cycloalkynyl, or C₆-C₁₀ aryl, wherein each C₁₋₂₀alkyl, C₂₋₂₀ alkenyl, C₂₋₂₀ alkynyl, C₃₋₁₀ cycloalkyl, C₄-C₂₀alkylcycloalkyl, C₄₋₁₀ cycloalkenyl, C₄₋₁₀ cycloalkynyl or C₆-C₁₀ arylis optionally substituted with one or more groups selected from —COOH,—COH, —SCH₃, —NH₂, ═NH, —NHC(═NH)NH₂, —C(═O)NH₂, —OH, 4-hydroxyphenyl,5-imidazolyl, 3-indolyl, halogen, —SO₃H, ═O, C₁₋₈ alkyl, C₃₋₈cycloalkyl, C₄₋₉ cycloalkylalkyl, phenyl, 4-methylphenyl, benzyl,—O—C₃₋₈ cyclalkyl, —O—C₃₋₈ cycloalkyl, —O—C₄₋₉ cycloalkylalkyl,—O-phenyl, —O-4-methylphenyl, —O-benzyl, —SO₂R⁷ or —NHR⁷ wherein R⁷ isH, C₁₋₈ alkyl, phenyl, 4-methylphenyl, benzyl or —NH₂, and wherein eachC₁₋₂₀ alkyl, C₂₋₂₀ alkenyl, C₂₋₂₀ alkynyl, C₃₋₁₀ cycloalkyl, C₄-C₂₀alkylcycloalkyl, C₄₋₁₀ cycloalkenyl, C₄₋₁₀ cycloalkynyl or C₆-C₁₀ aryloptionally contains one to three heteroatoms selected from N, O and S;

or R¹ and A, together with the nitrogen atom to which they are attached,form a 5- to 10-member heterocyclic ring or a 5- to 10-memberheteroaromatic ring in which the free electron pair of the nitrogen atomto which R¹ and A is attached is not part of the aromatic pi-electronsystem, the 5- to 10-member heterocyclic or heteroaromatic ring beingoptionally substituted by one or more groups selected from C₁₋₆ alkyl,C₃₋₈ cycloalkyl, halogen, hydroxy, —OC₁₋₆ alkyl or —OC₃₋₈ cycloalkyl;

or R¹ and R², together with the nitrogen atom to which they areattached, form a 5- to 10-member heterocyclic ring or a 5- to 10-memberheteroaromatic ring in which the free electron pair of the nitrogen atomto which R¹ and A is attached is not part of the aromatic pi-electronsystem, the 5- to 10-member heterocyclic or heteroaromatic ring beingoptionally substituted by one or more groups selected from C₁₋₆ alkyl,C₃₋₈ cycloalkyl, halogen, hydroxy, —OC₁₋₆ alkyl or —OC₃₋₈ cycloalkyl.

In accordance with some variations of this embodiment of the invention,Y is of the formula R¹R²N-A-COOH or R¹R²N-A-SO₃H, wherein:

A is a bond, straight-chain or branched C₁₋₂₀ alkyl, straight-chain orbranched C₂₋₂₀ alkenyl, straight-chain or branched C₂₋₂₀ alkynyl, C₃₋₁₀cycloalkyl, straight-chain or branched C₄-C₂₀ alkylcycloalkyl, C₄₋₁₀cycloalkenyl, C₄₋₁₀ cycloalkynyl, or C₆-C₁₀ aryl, wherein each C₁₋₂₀alkyl, C₂₋₂₀ alkenyl, C₂₋₂₀ alkynyl, C₃₋₁₀ cycloalkyl, C₄-C₂₀alkylcycloalkyl, C₄₋₁₀ cycloalkenyl, C₄₋₁₀ cycloalkynyl or C₆-C₁₀ arylis optionally substituted with one or more groups selected from —COOH,—COH, —SCH₃, —NH₂, ═NH, —NHC(═NH)NH₂, —C(═O)NH₂, —OH, 4-hydroxyphenyl,5-imidazolyl, 3-indolyl, halogen, —SO₃H, ═O, C₁₋₈ alkyl, C₃₋₈cycloalkyl, C₄₋₉ cycloalkylalkyl, phenyl, 4-methylphenyl, benzyl,—O—C₃₋₈ cyclalkyl, —O—C₃₋₈ cycloalkyl, —O—C₄₋₉ cycloalkylalkyl,—O-phenyl, —O-4-methylphenyl, —O-benzyl, SO₂R⁷ or —NHR⁷ wherein R⁷ is H,C₁₋₈ alkyl, phenyl, 4-methylphenyl, benzyl or —NH₂, and wherein eachC₁₋₂₀ alkyl, C₂₋₂₀ alkenyl, C₂₋₂₀ alkynyl, C₃₋₁₀ cycloalkyl, C₄-C₂₀alkylcycloalkyl, C₄₋₁₀ cycloalkenyl, C₄₋₁₀ cycloalkynyl or C₆-C₁₀ aryloptionally contains one to three heteroatoms selected from N, O and S;

R¹ and R² are each independently selected from the group consisting ofH, straight-chain or branched C₁₋₂₀ alkyl, straight-chain or branchedC₂₋₂₀ alkenyl, straight-chain or branched C₂₋₂₀ alkynyl, C₃₋₁₀cycloalkyl, straight-chain or branched C₄-C₂₀ alkylcycloalkyl, C₄₋₁₀cycloalkenyl, C₄₋₁₀ cycloalkynyl, or C₆-C₁₀ aryl, wherein each C₁₋₂₀alkyl, C₂₋₂₀ alkenyl, C₂₋₂₀ alkynyl, C₃₋₁₀ cycloalkyl, C₄-C₂₀alkylcycloalkyl, C₄₋₁₀ cycloalkenyl, C₄₋₁₀ cycloalkynyl or C₆-C₁₀ arylis optionally substituted with one or more groups selected from —COOH,—COH, —SCH₃, —NH₂, ═NH, —NHC(═NH)NH₂, —C(═O)NH₂, —OH, 4-hydroxyphenyl,5-imidazolyl, 3-indolyl, halogen, —SO₃H, ═O, C₁₋₈ alkyl, C₃₋₈cycloalkyl, C₄₋₉ cycloalkylalkyl, phenyl, 4-methylphenyl, benzyl,—O—C₃₋₈ cyclalkyl, —O—C₃₋₈ cycloalkyl, —O—C₄₋₉ cycloalkylalkyl,—O-phenyl, —O-4-methylphenyl, —O-benzyl, —SO₂R⁷ or —NHR⁷ wherein R⁷ isH, C₁₋₈ alkyl, phenyl, 4-methylphenyl, benzyl or —NH₂, and wherein eachC₁₋₂₀ alkyl, C₂₋₂₀ alkenyl, C₂₋₂₀ alkynyl, C₃₋₁₀ cycloalkyl, C₄-C₂₀alkylcycloalkyl, C₄₋₁₀ cycloalkenyl, C₄₋₁₀ cycloalkynyl or C₆-C₁₀ aryloptionally contains one to three heteroatoms selected from N, O and S;

or R¹ and A, together with the nitrogen atom to which they are attached,form a 5- to 10-member heterocyclic ring or a 5- to 10-memberheteroaromatic ring in which the free electron pair of the nitrogen atomto which R¹ and A is attached is not part of the aromatic pi-electronsystem, the 5- to 10-member heterocyclic or heteroaromatic ring beingoptionally substituted by one or more groups selected from C₁₋₆ alkyl,C₃₋₈ cycloalkyl, halogen, hydroxy, —OC₁₋₆ alkyl or —OC₃₋₈ cycloalkyl;

or R¹ and R², together with the nitrogen atom to which they areattached, form a 5- to 10-member heterocyclic ring or a 5- to 10-memberheteroaromatic ring in which the free electron pair of the nitrogen atomto which R¹ and A is attached is not part of the aromatic pi-electronsystem, the 5- to 10-member heterocyclic or heteroaromatic ring beingoptionally substituted by one or more groups selected from C₁₋₆ alkyl,C₃₋₈ cycloalkyl, halogen, hydroxy, —OC₁₋₆ alkyl or —OC₃₋₈ cycloalkyl.

In some variations of this embodiment of the invention, the bromide andthe nitrogen-containing compound are mixed to form a mixture of bromideand amine, which is diluted prior to mixing with the hypochlorite. Inother variations on this embodiment of the invention, the bromide isdiluted separately from the nitrogen-containing compound, and thebromide is diluted prior to mixing with the nitrogen-containing compoundand the hypochlorite.

In some variations of this embodiment of the invention, the bromide isan alkali or alkaline earth metal bromide salt or a mixture of alkali oralkaline earth metal bromide salts. In some variations of thisembodiment of the invention, the bromide is selected from the groupconsisting of HBr, LiBr, NaBr, KBr, CaBr₂ and MgBr₂ and mixturesthereof. In some variations of this embodiment of the invention, thebromide comprises a salt selected from the group consisting of sodiumbromide and potassium bromide. In some variations of this embodiment ofthe invention, the bromide comprises or is NaBr.

In some variations of this embodiment of the invention, the bromide andnitrogen-containing compound are present in a molar ratio of between20:1 and 1:10. In other variations of this embodiment of the invention,the bromide and nitrogen-containing compound are present in a molarratio of between 2:1 and 1:2. In some variations of this embodiment ofthe invention, the bromide and nitrogen-containing compound are presentin equimolar amounts. In some variations of this embodiment of theinvention, the molar ratio of primary amine groups in thenitrogen-containing compound to the bromide is between 1:10 and 20:1. Inother variations of this embodiment of the invention, the molar ratio ofprimary amine groups in the nitrogen-containing compound to the bromidein is between 1:2 and 2:1. In some variations of this embodiment of theinvention, the molar ratio of primary amine groups in thenitrogen-containing compound to the bromide is 1:1. In some variationsof this embodiment of the invention, the total amount of bromide andnitrogen-containing compound prior to dilution is between 10 and 40%w/v.

In accordance with some variations of this embodiment of the invention,the concentration of the hypochlorite oxidant in the aqueoushypochlorite oxidant solution immediately prior to mixing with thenitrogen-containing compound is not more than 24,000 ppm as totalchlorine. In accordance with some variations of this embodiment of theinvention, the concentration of the hypochlorite oxidant in the aqueoushypochlorite oxidant solution immediately prior to mixing with thenitrogen-containing compound is not more than 12,000 ppm as totalchlorine.

In accordance with some variations of this embodiment of the invention,the nitrogen-containing compound or mixture thereof is in an aqueoussolution at a concentration of 0.5-60% w/v prior to mixing with thehypochlorite oxidant solution.

In accordance with some variations of this embodiment of the invention,the mixing takes place in a mixing chamber into and out of which thereis a continuous flow of water during the mixing.

In accordance with some variations of this embodiment of the invention,the biocide is applied to the medium substantially as the biocide isformed. In accordance with other variations of this embodiment of theinvention, the biocide is applied to the medium within 30 seconds offormation of the biocide. In accordance with other variations of thisembodiment of the invention, the biocide is applied to the medium within60 seconds of formation of the biocide. In accordance with othervariations of this embodiment of the invention, the biocide is appliedto the medium within 90 seconds of formation of the biocide. Inaccordance with other variations of this embodiment of the invention,the biocide is applied to the medium within 120 seconds of formation ofthe biocide. In accordance with other variations of this embodiment ofthe invention, the biocide is applied to the medium within 150 secondsof formation of the biocide. In accordance with other variations of thisembodiment of the invention, the biocide is applied to the medium within180 seconds of formation of the biocide.

In accordance with some variations of this embodiment of the invention,the mixing chamber is a conduit.

In accordance with other variations of this embodiment of the invention,the mixing takes place in a mixing chamber out of which there is not acontinuous flow of water during the mixing. In accordance with othervariations of this embodiment of the invention, biocide is applied tothe medium substantially immediately upon completion of the mixing. Inaccordance with other variations of this embodiment of the invention,the biocide is applied to the medium within 30 seconds of completion ofthe mixing. In accordance with other variations of this embodiment ofthe invention, the biocide is applied to the medium within 60 seconds ofcompletion of the mixing. In accordance with other variations of thisembodiment of the invention, the biocide is applied to the medium within90 seconds of completion of the mixing. In accordance with othervariations of this embodiment of the invention, the biocide is appliedto the medium within 120 seconds of completion of the mixing. Inaccordance with other variations of this embodiment of the invention,the biocide is applied to the medium within 150 seconds of completion ofthe mixing. In accordance with other variations of this embodiment ofthe invention, the biocide is applied to the medium within 180 secondsof completion of the mixing.

In accordance with some variations of this embodiment of the invention,the hypochlorite oxidant is selected from the group consisting ofalkaline and alkali earth metal hypochlorites, hypochlorite released towater from a stable chlorine carrier and hypochlorite formed in situfrom chlorine gas, and mixtures thereof. In accordance with somevariations of this embodiment of the invention, the stable chlorinecarrier is selected from the group consisting of trichlorocyanuric acid,dichlorodimethylhydantoin and monochlorodimethylhydantoin. In accordancewith some variations of this embodiment of the invention, thehypochlorite oxidant is selected from the group consisting of lithiumhypochlorite, sodium hypochlorite, calcium hypochlorite, magnesiumhypochlorite and potassium hypochlorite. In accordance with somevariations of this embodiment of the invention, the hypochlorite oxidantis sodium hypochlorite.

In accordance with some variations of this embodiment of the invention,the nitrogen-containing compound is selected from the group consistingof carbamic acid, sulfamic acid, glycine, glutamine, arginine,histidine, lysine, and mixtures thereof.

In accordance with some variations of this embodiment of the invention,Y is selected from the group consisting of carbamic acid, sulfamic acid,glycine, glutamine, arginine, histidine, and lysine.

In accordance with some variations of this embodiment of the invention,the molar ratio of nitrogen atoms in the nitrogen-containing compound ormixture thereof to the hypochlorite oxidant is 1:1. In accordance withsome variations of this embodiment of the invention, the molar ratio ofthe nitrogen-containing compound to the hypochlorite oxidant is 1:1. Inaccordance with some variations of this embodiment of the invention, themolar ratio of nitrogen atoms in the nitrogen-containing compound ormixture thereof to the hypochlorite oxidant is greater than 1:1. Inaccordance with other variations of this embodiment of the invention,the molar ratio of the nitrogen-containing compound to the hypochloriteoxidant is greater than 1:1.

In accordance with some variations of this embodiment of the invention,the concentration of the hypochlorite oxidant in the aqueoushypochlorite oxidant solution prior to mixing with thenitrogen-containing compound is not more than 24,000 ppm as totalchlorine, and the mixing chamber comprises a conduit through which waterflows as the hypochlorite oxidant solution and the nitrogen-containingcompound are mixed. In accordance with some variations of thisembodiment of the invention, the concentration of the hypochloriteoxidant in the aqueous hypochlorite oxidant solution immediately priorto mixing with the nitrogen-containing compound is not more than 12,000ppm as total chlorine. In accordance with some variations of thisembodiment of the invention, the solution of hypochlorite oxidant isprepared in situ in the conduit prior to addition of the solution of thenitrogen-containing compound to the conduit.

In accordance with some variations of this embodiment of the invention,the nitrogen-containing compound is diluted prior to mixing with thehypochlorite oxidant.

In accordance with some variations of this embodiment of the invention,the biocide has a pH of between 8.0 and 11.5 immediately prior to beingapplied to the medium. In accordance with some variations of thisembodiment of the invention, the biocide has a pH of at least 8.5immediately prior to being applied to the medium. In accordance withsome variations of this embodiment of the invention, the biocide has apH of at least 9.0 immediately prior to being applied to the medium. Inaccordance with some variations of this embodiment of the invention, thebiocide has a pH of at least 9.5 immediately prior to being applied tothe medium. In accordance with some variations of this embodiment of theinvention, the biocide has a pH of at least 10.0 immediately prior tobeing applied to the medium. In accordance with some variations of thisembodiment of the invention, the biocide has a pH of at least 10.5immediately prior to being applied to the medium. In accordance withsome variations of this embodiment of the invention, the biocide has apH of at least 11.0 immediately prior to being applied to the medium. Inaccordance with some variations of this embodiment of the invention, thebiocide has a pH of no more than 11.5 immediately prior to being appliedto the medium.

In accordance with some variations of this embodiment of the invention,the medium is selected from the group consisting of pulp and paperfactory process water, cooling tower water, waste water, reclaimed wastewater, clay slurries, starch slurries, sludge, soil, colloidalsuspensions, and irrigation water. In accordance with some variations ofthis embodiment of the invention, the medium is pulp and paper factorywater. In accordance with some variations of this embodiment of theinvention, the medium is cooling tower water. In accordance with somevariations of this embodiment of the invention, the medium is wastewater. In accordance with some variations of this embodiment of theinvention, the medium is reclaimed waste water. In accordance with somevariations of this embodiment of the invention, the medium is a clayslurry. In accordance with some variations of this embodiment of theinvention, the medium is a starch slurry. In accordance with somevariations of this embodiment of the invention, the medium is a sludge.In accordance with some variations of this embodiment of the invention,the medium is soil. In accordance with some variations of thisembodiment of the invention, the medium is a colloidal suspension. Inaccordance with some variations of this embodiment of the invention, themedium is irrigation water. In accordance with some variations of thisembodiment of the invention, the medium is a medium containing strongreducing agents or having a high reducing capacity, viz. an ORP of notgreater than 150 millivolts.

In accordance with some variations of this embodiment of the invention,the biocide is applied to the medium periodically with a duty cycle ofless than 1:2. In accordance with some variations of this embodiment ofthe invention, the biocide is applied to the medium periodically with aduty cycle of between about 1:5 and 1:10. In accordance with somevariations of this embodiment of the invention, the biocide is appliedto the medium periodically with a duty cycle of less than 1:10. Inaccordance with some variations of this embodiment of the invention, thebiocide is applied to the medium periodically with a duty cycle of lessthan 1:25. In accordance with some variations of this embodiment of theinvention, the biocide is applied to the medium periodically with a dutycycle of less than 1:50.

In accordance with some variations of this embodiment of the invention,the biocide is applied to the medium at a rate to maintain in thebiocide a stable pH of at least 8.0 as the biocide is produced.

In accordance with some variations of this embodiment of the invention,the concentration of the biocide immediately prior to being applied tothe medium is from 1000 to 12,000 ppm expressed as total chlorine.

In accordance with some variations of this embodiment of the invention,the medium has a pH of between about 5 and about 11.5 before the biocideis applied to the medium. In accordance with some variations of thisembodiment of the invention, the medium has a pH of between about 6 andabout 10 before the biocide is applied to the medium. In accordance withsome variations of this embodiment of the invention, the medium has a pHof between about 7 and about 9 before the biocide is applied to themedium.

In accordance with some variations of this embodiment of the invention,the concentration of the biocide in the medium, upon application of thebiocide to the medium, is 0.5-300 ppm expressed as chlorine. Inaccordance with some variations of this embodiment of the invention, theconcentration of the biocide in the medium, upon application of thebiocide to the medium, is 1-10 ppm expressed as chlorine.

In accordance with some variations of this embodiment of the invention,the biocide is effective within 24 hours of application to the medium.In accordance with some variations of this embodiment of the invention,the biocide is effective within 1 hour of application to the medium. Inaccordance with some variations of this embodiment of the invention, thebiocide is effective within 20 minutes of application to the medium. Inaccordance with some variations of this embodiment of the invention, thebiocide is effective within 15 minutes of application to the medium.

In accordance with some variations of this embodiment of the invention,the biocide is capable of reducing microbial activity by at least 50%within 3 hours after administration. In accordance with some variationsof this embodiment of the invention, the biocide is capable of reducingmicrobial activity by at least 50% within 1 hour after administration.In accordance with some variations of this embodiment of the invention,the biocide is capable of reducing microbial activity by at least 50%within 30 minutes after administration. In the context of thesevariations of this embodiment of the invention, reduction in microbialactivity may be correlated to an increase in operational efficiency ofthe system being treated. For example, in a paper machine, a reductionin microbial activity will result in improved runnability of the papermachine. In some contexts, reduced microbial activity can be correlatedto decreased production of ATP or to decreased production of catalase.In accordance with some variations of this embodiment of the invention,after the recited time period there is a residual of biocide, expressedas total chlorine, of at least 0.5 ppm. In accordance with somevariations of this embodiment of the invention, after the recited timeperiod there is a residual of biocide, expressed as total chlorine, thatis too low to be measured. In accordance with some variations of thisembodiment of the invention, the reduction of microbial activity ismeasured in a test sample. In accordance with some variations of thisembodiment of the invention, the reduction of microbial activity ismeasured on site.

In accordance with some variations of this embodiment of the invention,the biocide is capable of reducing microbial activity by at least 75%within 3 hours after administration. In accordance with some variationsof this embodiment of the invention, the biocide is capable of reducingmicrobial activity by at least 75% within 1 hour after administration.In accordance with some variations of this embodiment of the invention,the biocide is capable of reducing microbial activity by at least 75%within 30 minutes after administration. In the context of thesevariations of this embodiment of the invention, reduction in microbialactivity may be correlated to an increase in operational efficiency ofthe system being treated. For example, in a paper machine, a reductionin microbial activity will result in improved runnability of the papermachine. In some contexts, reduced microbial activity can be correlatedto decreased production of ATP or to decreased production of catalase.In accordance with some variations of this embodiment of the invention,after the recited time period there is a residual of biocide, expressedas total chlorine, of at least 0.5 ppm. In accordance with somevariations of this embodiment of the invention, after the recited timeperiod there is a residual of biocide, expressed as total chlorine, thatis too low to be measured. In accordance with some variations of thisembodiment of the invention, the reduction of microbial activity ismeasured in a test sample. In accordance with some variations of thisembodiment of the invention, the reduction of microbial activity ismeasured on site.

In accordance with some variations of this embodiment of the invention,the biocide is capable of reducing microbial activity by at least 90%within 3 hours after administration. In accordance with some variationsof this embodiment of the invention, the biocide is capable of reducingmicrobial activity by at least 90% within 1 hour after administration.In accordance with some variations of this embodiment of the invention,the biocide is capable of reducing microbial activity by at least 90%within 30 minutes after administration. In the context of thesevariations of this embodiment of the invention, reduction in microbialactivity may be correlated to an increase in operational efficiency ofthe system being treated. For example, in a paper machine, a reductionin microbial activity will result in improved runnability of the papermachine. In some contexts, reduced microbial activity can be correlatedto decreased production of ATP or to decreased production of catalase.In accordance with some variations of this embodiment of the invention,after the recited time period there is a residual of biocide, expressedas total chlorine, of at least 0.5 ppm. In accordance with somevariations of this embodiment of the invention, after the recited timeperiod there is a residual of biocide, expressed as total chlorine, thatis too low to be measured. In accordance with some variations of thisembodiment of the invention, the reduction of microbial activity ismeasured in a test sample. In accordance with some variations of thisembodiment of the invention, the reduction of microbial activity ismeasured on site.

In accordance with some variations of this embodiment of the invention,the biocide is capable of killing at least 50% of the microorganisms ina liquid test sample within 3 hours after administration. In accordancewith some variations of this embodiment of the invention, the biocide iscapable of killing at least 50% of the microorganisms in a liquid testsample within 1 hour after administration. In accordance with somevariations of this embodiment of the invention, the biocide is capableof killing at least 50% of the microorganisms in a liquid test samplewithin 30 minutes after administration. In accordance with somevariations of this embodiment of the invention, after the recited timeperiod there is a residual of biocide, expressed as total chlorine, ofat least 0.5 ppm. In accordance with some variations of this embodimentof the invention, after the recited time period there is a residual ofbiocide, expressed as total chlorine, that is too low to be measured.

In accordance with some variations of this embodiment of the invention,the biocide is capable of killing at least 75% of the microorganisms ina liquid test sample within 3 hours after administration. In accordancewith some variations of this embodiment of the invention, the biocide iscapable of killing at least 75% of the microorganisms in a liquid testsample within 1 hour after administration. In accordance with somevariations of this embodiment of the invention, the biocide is capableof killing at least 75% of the microorganisms in a liquid test samplewithin 30 minutes after administration. In accordance with somevariations of this embodiment of the invention, after the recited timeperiod there is a residual of biocide, expressed as total chlorine, ofat least 0.5 ppm. In accordance with some variations of this embodimentof the invention, after the recited time period there is a residual ofbiocide, expressed as total chlorine, that is too low to be measured.

In accordance with some variations of this embodiment of the invention,the biocide is capable of killing at least 90% of the microorganisms ina liquid test sample within 3 hours after administration. In accordancewith some variations of this embodiment of the invention, the biocide iscapable of killing at least 90% of the microorganisms in a liquid testsample within 1 hour after administration. In accordance with somevariations of this embodiment of the invention, the biocide is capableof killing at least 90% of the microorganisms in a liquid test samplewithin 30 minutes after administration. In accordance with somevariations of this embodiment of the invention, after the recited timeperiod there is a residual of biocide, expressed as total chlorine, ofat least 0.5 ppm. In accordance with some variations of this embodimentof the invention, after the recited time period there is a residual ofbiocide, expressed as total chlorine, that is too low to be measured.

In accordance with some variations of this embodiment of the invention,the medium is present in a system from which a portion of the medium isdischarged and replaced during the regular course of operation of thesystem. In accordance with some variations of this embodiment of theinvention, the portion of the medium which is discharged and replacedduring the regular course of operation of the system is continuouslydischarged and replaced during the regular course of operation of thesystem. In accordance with some variations of this embodiment of theinvention, the portion of the medium which is discharged and replacedduring the regular course of operation of the system is discharged andreplaced at least once every 24 hours during the regular course ofoperation of the system.

There is also provided, in accordance with an embodiment of theinvention, an apparatus for introducing a biocide into a medium,comprising:

a nitrogen-containing compound containing reservoir containing anitrogen-containing compound which is selected from the group consistingof salts of the formula Y^(x−)[NH₂R³R⁴]⁺ _(x), salts of the formulaY^(x−)Z^(n+) _(x/n), and molecules Y per se, wherein Y, R³, R⁴, x, Z andn are as defined above;

a source of hypochlorite oxidant dilution having a concentration of notmore than 24,000 ppm as total chlorine;

a source of bromide dilution;

and a mixing chamber operable to mix the hypochlorite dilution, thebromide dilution and the nitrogen-containing compound in a molar ratioof nitrogen atoms in the nitrogen-containing compound to hypochlorite ofat least 1:1, to produce the biocide in the mixing chamber.

In some variations of this embodiment of the invention, the source ofhypochlorite oxidant dilution has a concentration of not more than12,000 ppm as total chlorine.

In some variations of this embodiment of the invention, Y is selectedfrom the group consisting of straight, branched and cyclic moleculescontaining at least one moiety selected from the group consisting of anamide moiety, an imide moiety, a sulfamide moiety, a sulfimide moiety,and an amineimine moiety, and Y^(x−) is basic form of the molecule. Insome variations of this embodiment of the invention, at least one of theat least one amide moiety, imide moiety, sulfamide moiety, sulfimidemoiety, or amineimine moiety is ionized to the corresponding anionicform.

In some variations of this embodiment of the invention, Y is anamphoteric molecule containing at least one moiety selected from thegroup consisting of COOH and SO₃H and at least one moiety selected fromthe group consisting of a primary amine moiety, a secondary aminemoiety, and a tertiary amine moiety, and Y^(x−) is an anionic form ofthe amphoteric molecule. In some variations of this embodiment of theinvention, at least one of the at least one COOH and SO₃H is ionized tothe corresponding anionic form.

In some variations of this embodiment of the invention, Q is anamphoteric molecule containing at least one moiety selected from thegroup consisting of COOH and SO₃H and at least one moiety selected fromthe group consisting of a primary amine moiety, a secondary aminemoiety, and a tertiary amine moiety, and Y^(x−) is an anionic form ofthe amphoteric molecule.

In accordance with some variations of this embodiment of the invention,the source of hypochlorite oxidant dilution comprises ahypochlorite-containing reservoir containing a hypochlorite oxidantsolution, and a diluter operable to dilute the hypochlorite oxidantsolution to produce the hypochlorite oxidant dilution having aconcentration of not more than 24,000 ppm expressed as total chlorine.In accordance with some variations of this embodiment of the invention,the diluter is operable to dilute the hypochlorite oxidant solution toproduce the hypochlorite oxidant dilution having a concentration of notmore than 12,000 ppm as total chlorine. In accordance with somevariations of this embodiment of the invention, the diluter and themixing chamber are a single conduit which is adapted to dilute thehypochlorite oxidant prior to mixing with the salt or mixture of salts.

In accordance with some variations of this embodiment of the invention,the nitrogen-containing compound is present in the nitrogen-compoundcontaining reservoir as an aqueous solution.

In accordance with some variations of this embodiment of the invention,the bromide is present in the nitrogen-containing compound containingreservoir. In accordance with some variations of this embodiment of theinvention, the bromide is present in a separate reservoir.

In accordance with some variations of this embodiment of the invention,the source of bromide dilution comprises a bromide-containing reservoircontaining a bromide solution, and a diluter operable to dilute thebromide solution to produce the bromide dilution. In accordance withsome variations of this embodiment of the invention, the diluter whichthe dilutes the bromide and the diluter which dilutes the oxidant andthe mixing chamber are a single conduit which is adapted to dilute thehypochlorite oxidant prior to mixing with the nitrogen-containingcompound and prior to mixing with the bromide.

In accordance with some variations of this embodiment of the invention,the molar ratio of nitrogen atoms in the nitrogen-containing compound ormixture thereof to the hypochlorite oxidant is 1:1. In accordance withsome variations of this embodiment of the invention, the molar ratio ofthe nitrogen-containing compound to the hypochlorite oxidant is 1:1. Inaccordance with some variations of this embodiment of the invention, themolar ratio of nitrogen atoms in the nitrogen-containing compound ormixture thereof to the hypochlorite oxidant is greater than 1:1. Inaccordance with other variations of this embodiment of the invention,the molar ratio of the nitrogen-containing compound to the hypochloriteoxidant is greater than 1:1.

In some variations of this embodiment of the invention, the bromide andnitrogen-containing compound are present in a molar ratio of between20:1 and 1:10. In other variations of this embodiment of the invention,the bromide and nitrogen-containing compound are present in a molarratio of between 2:1 and 1:2. In some variations of this embodiment ofthe invention, the bromide and nitrogen-containing compound are presentin equimolar amounts. In some variations of this embodiment of theinvention, the molar ratio of primary amine groups in thenitrogen-containing compound to the bromide is between 1:10 and 20:1. Inother variations of this embodiment of the invention, the molar ratio ofprimary amine groups in the nitrogen-containing compound to the bromidein is between 1:2 and 2:1. In some variations of this embodiment of theinvention, the molar ratio of primary amine groups in thenitrogen-containing compound to the bromide is 1:1. In some variationsof this embodiment of the invention, the total amount of bromide andnitrogen-containing compound prior to dilution is between 10 and 40%w/v.

In accordance with some variations of this embodiment of the invention,the system further comprises an egress adapted to enable introduction ofthe biocide from the mixing vessel into the medium.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are more particularly described withrespect to a number of examples set forth below, and also with respectto the accompanying drawings wherein:

FIG. 1 depicts an apparatus constructed and operative to enable thepractice of embodiments of the present invention; and

FIG. 2 depicts another apparatus constructed and operative to enable thepractice of embodiments of the present invention.

The apparatus illustrated in FIG. 1 produces a biocide that isintroduced into or applied to a medium 3, such as water, at one or morelocations 2. In some embodiments of the invention, the biocide is formedby mixing a hypochlorite oxidant and a salt of a nitrogen-containingcompound that contains at least one moiety selected from the groupconsisting of a primary amine moiety, a secondary amine moiety, atertiary amine moiety, an amide moiety, an imide moiety, a sulfamidemoiety, a sulfimide moiety, and an amineimine moiety, or a mixture ofsuch salts. In some embodiments of the invention, the salt is of theformula Y^(x−)[NH₂R³R⁴]⁺ _(x), wherein

Y^(x−) is a basic form of an acid Y that contains at least one moietyselected from the group consisting of a primary amine moiety, asecondary amine moiety, a tertiary amine moiety, an amide moiety, animide moiety, a sulfamide moiety, a sulfimide moiety, and an amineiminemoiety; and

[NH₂R³R⁴]⁺ is an acidic form of a base NHR³R⁴ wherein:

R³ and R⁴ are each independently selected from the group consisting of Hand C₁₋₈ alkyl,

or R³ and R⁴, together with the nitrogen atom to which they areattached, form a 5- to 10-member heterocyclic ring optionallysubstituted by one or more groups selected from C₁₋₆ alkyl, C₃₋₈cycloalkyl, halogen, hydroxy, —OC₁₋₆ alkyl or —OC₃₋₈ cycloalkyl; and

x is 1 to 3.

In some embodiments of the invention, Y is selected from the groupconsisting of straight, branched and cyclic molecules containing atleast one moiety selected from the group consisting of an amide moiety,an imide moiety, a sulfamide moiety, a sulfimide moiety, and anamineimine moiety. In some of these embodiments of the invention, Y^(x−)is a basic form of Y. In some of these embodiments of the invention, atleast one of the at least one amide moiety, imide moiety, sulfamidemoiety, sulfimide moiety, or amineimine moiety is ionized to thecorresponding anionic form.

In some embodiments of the invention, Y is selected from the groupconsisting of amphoteric molecules containing at least one moietyselected from the group consisting of a primary amine moiety, asecondary amine moiety, and a tertiary amine moiety, and at least onemoiety selected from the group consisting of COOH and SO₃H. In some ofthese embodiments of the invention, Y^(x−) is an anionic form of theamphoteric molecule. In some of these embodiments of the invention, atleast one of the at least one COOH and SO₃H is ionized to thecorresponding anionic form. In some embodiments of the invention, Y^(x−)is of the formula [R¹R²N-A-COO]^(x−) or [R¹R²N-A-SO₃]^(x−), wherein:

A is a bond, straight-chain or branched C₁₋₂₀ alkyl, straight-chain orbranched C₂₋₂₀ alkenyl, straight-chain or branched C₂₋₂₀ alkynyl, C₃₋₁₀cycloalkyl, straight-chain or branched C₄-C₂₀ alkylcycloalkyl, C₄₋₁₀cycloalkenyl, C₄₋₁₀ cycloalkynyl, or C₆-C₁₀ aryl, wherein each C₁₋₂₀alkyl, C₂₋₂₀ alkenyl, C₂₋₂₀ alkynyl, C₃₋₁₀ cycloalkyl, C₄-C₂₀alkylcycloalkyl, C₄₋₁₀ cycloalkenyl, C₄₋₁₀ cycloalkynyl or C₆-C₁₀ arylis optionally substituted with one or more groups selected from —COOH,—COH, —SCH₃, —NH₂, ═NH, —NHC(═NH)NH₂, —C(═O)NH₂, —OH, 4-hydroxyphenyl,5-imidazolyl, 3-indolyl, halogen, —SO₃H, ═O, C₁₋₈ alkyl, C₃₋₈cycloalkyl, C₄₋₉ cycloalkylalkyl, phenyl, 4-methylphenyl, benzyl,—O—C₃₋₈ cyclalkyl, —O—C₃₋₈ cycloalkyl, —O—C₄₋₉ cycloalkylalkyl,—O-phenyl, —O-4-methylphenyl, —O-benzyl, —SO₂R⁷ or —NHR⁷ wherein R⁷ isH, C₁₋₈ alkyl, phenyl, 4-methylphenyl, benzyl or —NH₂, and wherein eachC₁₋₂₀ alkyl, C₂₋₂₀ alkenyl, C₂₋₂₀ alkynyl, C₃₋₁₀ cycloalkyl, C₄-C₂₀alkylcycloalkyl, C₄₋₁₀ cycloalkenyl, C₄₋₁₀ cycloalkynyl or C₆-C₁₀ aryloptionally contains one to three heteroatoms selected from N, O and S;

R¹ and R² are each independently selected from the group consisting ofH, straight-chain or branched C₁₋₂₀ alkyl, straight-chain or branchedC₂₋₂₀ alkenyl, straight-chain or branched C₂₋₂₀ alkynyl, C₃₋₁₀cycloalkyl, straight-chain or branched C₄-C₂₀ alkylcycloalkyl, C₄₋₁₀cycloalkenyl, C₄₋₁₀ cycloalkynyl, or C₆-C₁₀ aryl, wherein each C₁₋₂₀alkyl, C₂₋₂₀ alkenyl, C₂₋₂₀ alkynyl, C₃₋₁₀ cycloalkyl, C₄-C₂₀alkylcycloalkyl, C₄₋₁₀ cycloalkenyl, C₄₋₁₀ cycloalkynyl or C₆-C₁₀ arylis optionally substituted with one or more groups selected from —COOH,—COH, —SCH₃, —NH₂, ═NH, —NHC(═NH)NH₂, —C(═O)NH₂, —OH, 4-hydroxyphenyl,5-imidazolyl, 3-indolyl, halogen, —SO₃H, ═O, C₁₋₈ alkyl, C₃₋₈cycloalkyl, C₄₋₉ cycloalkylalkyl, phenyl, 4-methylphenyl, benzyl,—O—C₃₋₈ cyclalkyl, —O—C₃₋₈ cycloalkyl, —O—C₄₋₉ cycloalkylalkyl,—O-phenyl, —O-4-methylphenyl, —O-benzyl, —SO₂R⁷ or —NHR⁷ wherein R⁷ isH, C₁₋₈ alkyl, phenyl, 4-methylphenyl, benzyl or —NH₂, and wherein eachC₁₋₂₀ alkyl, C₂₋₂₀ alkenyl, C₂₋₂₀ alkynyl, C₃₋₁₀ cycloalkyl, C₄-C₂₀alkylcycloalkyl, C₄₋₁₀ cycloalkenyl, C₄₋₁₀ cycloalkynyl or C₆-C₁₀ aryloptionally contains one to three heteroatoms selected from N, O and S;

or R¹ and A, together with the nitrogen atom to which they are attached,form a 5- to 10-member heterocyclic ring or a 5- to 10-memberheteroaromatic ring in which the free electron pair of the nitrogen atomto which R¹ and A is attached is not part of the aromatic pi-electronsystem, the 5- to 10-member heterocyclic or heteroaromatic ring beingoptionally substituted by one or more groups selected from C₁₋₆ alkyl,C₃₋₈ cycloalkyl, halogen, hydroxy, —OC₁₋₆ alkyl or —OC₃₋₈ cycloalkyl;

or R¹ and R², together with the nitrogen atom to which they areattached, form a 5- to 10-member heterocyclic ring or a 5- to 10-memberheteroaromatic ring in which the free electron pair of the nitrogen atomto which R¹ and A is attached is not part of the aromatic pi-electronsystem, the 5- to 10-member heterocyclic or heteroaromatic ring beingoptionally substituted by one or more groups selected from C₁₋₆ alkyl,C₃₋₈ cycloalkyl, halogen, hydroxy, —OC₁₋₆ alkyl or —OC₃₋₈ cycloalkyl.

In other embodiments of the invention, the salt is of the formY^(x−)Z^(n+) _(x/n), wherein Y^(x−) is as defined above, and Z^(n+) is acation other than a cation of the form [NH₂R³R⁴]⁺ as defined above, andn is a whole number greater than zero.

In other embodiments of the invention, the hypochlorite is mixed with anitrogen containing compound which is not a salt but is a compound Y perse as defined above, provided that the compound Y is not sulfamic acid,melamine, cyanuric acid, hydantoin, dialkyl hydantoin such as dimethylhydantoin, biuret, succinamide, succinimide, creatine, or creatinine.

As will be explained hereinbelow, in some embodiments of the invention,in forming the biocide the hypochlorite and nitrogen-containing compoundor salt thereof are also mixed with a bromide.

In FIG. 1, reservoir 4 contains a solution of hypochlorite, andreservoir 6 contains a solution of the nitrogen-containing compound orsalt thereof. In some embodiments of the invention, the solutioncontained in reservoir 6 also comprises bromide.

As shown in FIG. 1, water is fed from a source 8, shown in FIG. 1 as areservoir 8 from which water is pumped by pump 70, via a water pipe 10through parallel flow meters 72 and into a corresponding pair of branchlines 12, 14, which connect to a mixer 21 which feeds common outlet pipe16 leading to medium 3 at the locations 2. A low-water flow switch 71 isoperably connected to the flow indicator 72 of line 12. Outlet pipe 16is equipped with a siphon breaker 86, and may also be equipped with a pHmeter 47 to monitor the pH of the biocide.

Pumps P₁ and P₂, which may be for example pusaltile pumps, peristalticpumps, other types of pumps or the equivalents of pumps (such asventuris) as are known in the art, pump the hypochlorite andnitrogen-containing compound or salt thereof from reservoirs 4 and 6respectively through lines 75 and 73 respectively into lines 14 and 12at junction pieces 82 and 80, respectively. These junction pieces maybe, for example, simple T-connectors, or they may be designed tofacilitate mixing of the solutions from reservoirs 4 and 6 with thewater flowing through lines 14 and 12. Between reservoirs 6 and 4 arecalibration tubes 76 and 84 and valves 74.

Thus, depending on the concentration of the components in reservoirs 4and 6, the rate at which these components are pumped into lines 14 and12 respectively, and the rate of flow of water through lines 12 and 14,the hypochlorite oxidant and nitrogen-containing compound or saltthereof may be diluted and mixed in desired proportions. The reactionproduct, namely the biocide produced by the reaction of the hypochloriteand nitrogen-containing compound or salt thereof, may thus be applieddirectly from outlet pipe 16 into the medium 3, within a brief timeafter the formation of the biocide. In alternative embodiments of theinvention (not shown), mixer 21 is replaced by a ingress chamber or ajunction piece, in which case the dilutions mix and react as they flowthrough outlet pipe 16, so that by the time the fluid flowing throughoutlet pipe 16 is introduced into the liquid 3, the biocide has beenproduced. In these alternative embodiments of the invention, outlet pipe16 rather than mixer 21 functions as a mixing chamber.

It will also be appreciated that although as depicted in FIG. 1, thesolution of nitrogen-containing compound or salt thereof is dilutedprior to mixing with the hypochlorite oxidant dilution, in thoseembodiments of the invention in which bromide is not employed, thissolution need not be diluted prior to mixing with the hypochloritedilution. Irrespective of whether the nitrogen-containing compound orsalt thereof is diluted or not before mixing with the hypochlorite, thenitrogen-containing compound or salt thereof should be mixed with thehypochlorite oxidant in equimolar amounts or in a molar excess relativeto the hypochlorite oxidant. It will also be appreciated that in someembodiments, the concentration of hypochlorite immediately prior tomixing with the nitrogen-containing compound or salt thereof does notexceed 24,000 ppm expressed as total chlorine, and that in someembodiments, the concentration of biocide prior to application to themedium does not exceed 12,000 ppm expressed as total chlorine.

Irrespective whether or not a mixer 21 is utilized, the flow throughoutlet pipe 16 should be sufficiently fast that the biocide does nothave time to decompose prior to introduction into the medium 3. In manyembodiments of the invention, the time from which the diluted oxidant,nitrogen-containing compound or salt thereof, and if present, dilutedbromide are mixed with each other to form the biocide until the biocideis injected from pipe 16 into medium 3 is three minutes or less. In someembodiments, the time is two-and-a-half minutes or less, in someembodiments the time is two minutes or less, in some embodiments thetime is one-and-a-half minutes or less, in some embodiments the time isone minute or less, and in some embodiments the time is 30 seconds orless. In other embodiments of the invention in which the biocide isstable for more than a few minutes, the biocide may be stored (e.g. in areservoir, not shown) prior to application to the medium.

The two branch lines 12, 14 include control valves 22, 24, which enablethe flow rate of the water through lines 12 and 14 to be controlled.

The control of the foregoing valves and pumps may be done by a controlsystem (not shown). Outlet line 16, therefore, may also include a pHsensor 47 for sensing the pH of the biocide, which may give feedback tothe control system to enable control of biocide production in responsethereto. The control system may control the supply of the water fromsource 8 via an electrical valve 48. The apparatus may also beconfigured with alarms or other signalling devices, such as flow switch71, which may give feedback to the control system. The illustratedsystem may further include a timer (not shown) which is pre-settable tofix both the lengths of time for which the biocide is to be fed via theoutlet line 16 to the medium to be treated, as well as the timeintervals between such feedings of the biocide. The control system mayalso be operative to control the operation of mixer 21.

The water supply line 10 from the water source 8 to the two branch lines12, 14, may include additional control devices, such as a flow meter 58for indicating the flow rate or flow volume.

As indicated earlier, the solution in reservoir 4 comprises ahypochlorite oxidant, and the solution within reservoir 6 comprises atleast one nitrogen-containing compound or salt thereof and, in someembodiments of the invention, bromide. When present, the bromide may beprovided in any suitable form. In some embodiments of the invention, thebromide is provided as an alkali or alkaline earth metal bromide salt,such as lithium bromide, sodium bromide, potassium bromide, calciumbromide, magnesium bromide or hydrobromic acid.

The oxidant may be chosen from alkali and alkaline earth metalhypochlorites, e.g. lithium hypochlorite, sodium hypochlorite, potassiumhypochlorite, calcium hypchlorite or magnesium hypochlorite.

In some embodiments of the invention, the biocide has a pH of at least8.0 immediately prior to its application to medium 3. In someembodiments of the invention, the biocide has a pH of at least 9.5immediately prior to its application to medium 3. In some embodiments ofthe invention, the biocide has a pH of at least 10.0 immediately priorto its injection into medium 3. In some embodiments of the invention,the biocide has a pH of at least 10.5 immediately prior to itsapplication to medium 3. In some embodiments of the invention, thebiocide has a pH of at least 11.0 immediately prior to its applicationto medium 3. In some embodiments of the invention, the biocide has a pHof not more than 11.5 immediately prior to its application to medium 3.In an embodiment of the invention, the biocide is applied at a rate tomaintain in the biocide a stable pH of at least 8.0 as it is produced.

FIG. 2 is similar to FIG. 1, with like numbers denoting elements of thesystem of FIG. 2 which are the same as in the system of FIG. 1 and whichoperate in the same way. In FIG. 2, only a single flow line 12 is used,and no mixer 21 is present. The solution from reservoir 4 is introducedinto line 12 upstream of where the solution from reservoir 6 isintroduced into the flow line. In this arrangement, the dilution of thenitrogen-containing compound or salt thereof, with or without bromide,may form in the presence of the oxidant dilution, as long as the molarratio of nitrogen-containing compound or salt thereof to hypochloriteoxidant is at least 1:1. The dilutions mix as they flow through line 12and out through pipe 16, which as shown in FIG. 2 constitutes acontinuation of line 12.

In variations of what is depicted in FIG. 1, bromide may be diluted andintroduced into mixer 21 separately from the nitrogen-containingcompound. In variations of what is depicted in FIG. 2, bromide may beintroduced to line 12 separately from the nitrogen-containing compound,provided that the bromide not introduced into line 12 upstream of wherethe nitrogen-containing is introduced into line 12.

It will be appreciated that in embodiments of the invention shownherein, the hypochlorite oxidant is diluted prior to mixing with thenitrogen-containing compound or salt thereof.

In the context of this patent application, the term “effective”, whenused in reference to a biocide, means that the biocide is capable ofcontrolling microbial growth, as evidenced by the ability to kill atleast 50% of the microorganism in a liquid test sample within 3 hoursafter administration, with a residual of biocide, expressed as totalchlorine, of at least 0.5 ppm.

In the present application, the term “duty cycle” will be understood tomean the ratio between (a) the amount of time a biocide is administeredto the water to be treated and (b) the amount of time the biocide is notadministered to the water to be treated.

It will also be appreciated that in the context of biofilm control, inembodiments of the invention it may not be necessary to killmicroorganisms within the biofilm in order to control the biofilm, andthat biofilm control in such cases can be adduced from directobservation of reduction of the presence of biofilm, or from observationof, for example, reduced production of ATP, reduced production ofcatalase, or other measurable variables which can be correlated withbiofilm control or improved operational efficiency of the system beingtreated.

The present invention will be better understood through the followingillustrative and non-limitative examples of embodiments thereof.

EXPERIMENTAL Series 1

General: Tests were conducted in an aqueous test system consisting ineach instance of deionized (DI) water to which starch (˜7.5 g/l),calcium hydroxide (94 ppm), and sodium bicarbonate (1320 ppm) was added;pH was adjusted to 8.17 using hydrochloric acid. A suspension ofmicroorganisms was prepared from a sample of pink slime removed from thesurface of a paper machine. Microorganisms (MOs) were grown at 37° C.

As controls, in each test (a) biocide was added to DI water only, and(b) a sample of medium was left untreated by biocide.

In the following examples, biocides in accordance with embodiments ofthe present invention were prepared by simulating production of thebiocides as described above. An appropriate volume of the solutioncontaining the biocide was added to each test container, taking intoaccount the final desired concentration of the biocide after addition tothe test container. The decomposition rate of the biocidal activeingredient was monitored in the examples below by measuring the residueof total chlorine in the concentrate.

Example 1 Oxidation Reduction Potential (ORP)

Using an ORP electrode (WTW), oxidation-reduction potentials weremeasured in accordance with G. Degramont, “Water Treatment Handbook”,Springer-Verlag, 1991, pp. 249-250, the contents of which areincorporated herein by reference.

In this example, four tests were conducted:

Test 1: In accordance with U.S. Pat. No. 6,478,972 (“Shim”), sodiumsulfamate (14.62 g sulfamic acid dissolved in 100 ml DI water containing7.2 g NaOH) and sodium hypochlorite (10.5% w/v expressed as Cl₂,commercial solution) were mixed (molar ratio of sulfamate to Cl₂1.007:1) to produce what Shim terms a “stabilized hypochloritesolution”. The resulting mixture was immediately added to each of theaqueous test systems, in defined volumes to maintain feed levels of 4.2,8.4 and 12.6 ppm (expressed as total chlorine) respectively.

Test 2: In accordance with Shim, sodium sulfamate (14.62 g sulfamic aciddissolved in 100 ml DI water containing 7.2 g NaOH) and sodiumhypochlorite (10.5% w/v expressed as Cl₂, commercial solution) weremixed (molar ratio of sulfamate to Cl₂ 1.007:1) to produce what Shimterms a “stabilized hypochlorite solution”. Sodium bromide (15.5% w/v)(molar ratio of Br⁻ to Cl₂ 1.014:1) was mixed into the “stabilizedhypochlorite solution”. A slight color change was noted as soon as NaBrwas added to the “stabilized hypochlorite concentrate”. An appropriatevolume of the resulting mixture was immediately added to each of theaqueous test systems, in defined volumes to maintain feed levels of 4.2,8.4 and 12.6 ppm (expressed as total chlorine) respectively.

Test 3: In accordance with Shim, sodium sulfamate (14.62 g sulfamic aciddissolved in 100 ml DI water) and sodium hypochlorite (10.5% w/vexpressed as Cl₂, commercial solution) were mixed (molar ratio ofsulfamic acid to Cl₂ 1.007:1) to produce what Shim terms a “stabilizedhypochlorite solution”. Sodium bromide (15.5% w/v) was mixed into the“stabilized hypochlorite solution” (molar ratio of Br⁻ to Cl₂ 1.014:1) Asignificant color change was noted as soon as NaBr was added to the“stabilized hypochlorite solution”. The resulting mixture wasimmediately added to each of the aqueous test systems, in definedvolumes to maintain feed levels of 4.2, 8.4, and 12.6 ppm (expressed astotal chlorine) respectively.

Test 4: In accordance with Shim, sulfamic acid (14.62 g in 100 ml DIwater) and sodium hypochlorite (10.5% w/v expressed as Cl₂, commercialsolution) were mixed. The mixture was immediately added to each of theaqueous test systems, in defined volumes to maintain feed levels of 4.2,8.4 and 12.6 ppm (expressed as total chlorine) respectively. NaBr (15.5%w/v, molar ratio of Br⁻ to Cl₂ 1.014:1) was simultaneously addedseparately to the aqueous system.

In tests 2, 3 and 4, ORP was measured two hours after the biocide wasadded to the aqueous system. The results are presented in Table 1, whereppm refers to the biocide feed level, expressed as Cl₂:

TABLE 1 ORP (millivolts) Treatment test 4 test 2 test 3 8.4 ppm, DI only340 405 420 4.2 ppm 238 310 348 8.4 ppm 231 294 330 12.6 ppm  250 284295   0 ppm 200 200 200

The results in Table 1 show that the order and mode of addition of thechemicals in the method of Shim is significant, as is the identity ofthe chemicals.

Example 2 Residual Total Chlorine

Residual total chlorine in the aqueous system was measured 10 minutesand 24 hours after addition of biocide, using the DPD colorimetricmethod (see “Standard Methods for Examination of Waste and Waste Water”,17^(th) Edition (1989), pp. 4-62 to 4-64, the contents of which areincorporated herein by reference). As is known in the art, the rate ofdegradation of an oxidizer in an aqueous system is system-specific, i.e.the degradation rate of a given oxidizer is reproducible in a givenaqueous system.

Test 4 is the same Test 4 conducted in Example 1.

Test 5: In accordance with an embodiment of the present invention,sodium sulfamate (14.62 g sulfamic acid dissolved in 100 ml DI watercontaining 7.2 g NaOH) was mixed with NaBr (15.5 g in 100 ml DI water)(sodium sulfamate and NaBr both equimolar to sodium hypochlorite) anddiluted in DI water. Sodium hypochlorite (10.5% w/v, expressed as Cl₂)was diluted in DI water (to a concentration of 4200 ppm, 0.42% w/vexpressed as Cl₂, equimolar to sulfamate and to bromide ion). The twodiluted solutions were mixed according to the procedure described above.The biocide was immediately added to the aqueous system at a feed levelof 2.1, 4.2 and 6.3 ppm expressed as total chlorine. The results arepresented in Table 2 (presented as total chlorine as percent of feed).

TABLE 2 Total Cl₂ (as % of feed) test 5 - test 5 - treatment test 4 - 10min test 4 - 24 hours 10 min 24 hours 8.4 ppm, DI 48.8 53.6 4.2 ppm, DI119.05 107.1 2.1 ppm 42.86 2.4 4.2 ppm 31 19.05 57.14 50 6.3 ppm 71.457.1 8.4 ppm 29.8 27.4 12.6 ppm  39.7 34.1 *In the control sample inwhich biocide treatment wa 0 ppm, the total Cl₂ was 0 ppm after both 10minutes and 24 hours.

These results show that biocide formed according to Shim et al. isdifferent than biocide formed in accordance with an embodiment of thepresent invention.

Example 3 Adenosine Triphosphate (ATP) Concentration

ATP levels serve as a measure for the biochemical activity ofmicroorganisms, and as such serve as a good model for the viability of amicrobial culture after it has been exposed to a biocide. Thus, in theaqueous system of Tests 4 and 5 described above, the concentration ofATP was measured 20 minutes after the addition of the biocide. Theresults are presented in Table 3.

TABLE 3 test 4 test 5 treatment ATP (ng/ml) ATP (ng/ml) 2.1 ppm 0.58 4.2ppm 0.75 0.53 6.3 ppm 0.44 8.4 ppm 0.7 12.6 ppm  0.56   0 ppm 0.61 0.61

The results presented in Table 3 show that after a contact time of 20minutes, the biocide produced according to the procedure of Shim et al.(sodium hypochlorite stabilized with sulfamic acid added to water to betreated, then NaBr added thereafter to the water to be treated) is lesseffective in controlling microbial activity than the biocide produced inaccordance with an embodiment of the present invention from sodiumsulfamate, sodium bromide and sodium hypochlorite. This result is inaccordance with the data presented by Shim, who states thatantimicrobial efficacy of his product occurs only 24 hours or more afteradministration to the water to be treated.

Example 4 Total Aerobic Counts

General procedure for conducting viable count tests in this and otherexamples, unless noted otherwise: 10-fold serial dilutions of each ofthe following aqueous system test samples in sterile saline containingsodium thiosulfate were prepared 30 minutes after the biocide was addedto the aqueous systems; the resulting serially ten-fold dilutedsolutions were mixed in the appropriate agar; colonies in the agar werecounted after 48 hours incubation at 30° C., and are presented ascfu/ml.

Test 5 is the same test 5 conducted in Examples 2 and 3 above.

Test 6: A biocide was prepared by diluting a solution of sodiumsulfamate (prepared from 14.62 g sodium sulfamate in 100 ml DI watercontaining 7.2 g NaOH, 5850 ppm) in DI water to produce a dilutionequimolar to 4200 ppm chlorine, diluting sodium hypochlorite in DI water(to a concentration of 4200 ppm, 0.42% w/v), mixing the two dilutionsand immediately adding an appropriate volume of the mixture to theaqueous system to be treated, as described above.

Samples for viable counts of aerobic MOs were taken after a contact timeof 30 minutes. Results of Tests 5 and 6 are presented in Tables 4 and4A.

TABLE 4 treatment Test 6 test 5 dosage, Cl₂ Aerobic cfu/ml aerobiccfu/ml 2.1 ppm 1.30 × 10⁵ 5.86 × 10⁴   0 ppm 1.30 × 10⁵ 1.30 × 10⁵ cfu =colony forming units

TABLE 4A treatment Test 6 test 5 dosage, Cl₂ aerobic cfu/ml (% kill)Aerobic cfu/ml (% kill) 2.1 ppm 0% 55%

The results in Tables 4 and 4A demonstrate that producing a biocide byfirst producing a dilute mixture of bromide and sulfamate, then mixingthis mixture with dilute hypochlorite and injecting the product into theliquid to be treated, while ensuring that there is no excess oxidant(hypochlorite) during the production of the biocide, yields a moreefficacious biocide than does mixing a dilute sulfamate with dilutehypochlorite and injecting the product into the liquid to be treated.

Example 5 Viable Counts in Media Containing High Sugars

Test 7: A biocide was prepared by dissolving guanidinium sulfate in DIwater (0.647 g guanidinium sulfate (MW 216.22) in 100 ml DI water),diluting sodium hypochlorite in DI water (to a concentration of 4200ppm, 0.42% w/v expressed as Cl₂), mixing the two dilutions andimmediately adding an appropriate volume of the mixture to the aqueoussystem to be treated, as described above.

Test 8: A biocide was prepared by mixing guanidinium sulfate (0.647 g)with NaBr (0.62 g, NaBr equimolar to sodium hypochlorite) in 100 ml DIwater, diluting sodium hypochlorite in DI water (to a concentration of4200 ppm, 0.42% w/v expressed as Cl₂), mixing the two dilutions andimmediately adding an appropriate volume of the mixture to the aqueoussystem to be treated. The results are shown in Table 5, which shows thenumber of sugar-consuming colony forming units (cfu), and Table 5A,which present the same data as % survival relative to the non-biocidetreated control.

TABLE 5 Test 7 test 8 treatment Sugar cfu/ml sugar cfu/ml 4.2 ppm, DIonly 0 0 2.1 ppm 9.20 × 10² 3.30 × 10² 4.2 ppm 9.80 × 10² 4.00 × 10  6.3ppm 8.00 × 10 5.00 × 10    0 ppm 1.06 × 10⁴ 1.06 × 10⁴

TABLE 5A Test 7 test 8 treatment sugar cfu/ml % survival sugar cfu/ml %survival 2.1 ppm 8.68 3.11 4.2 ppm 9.25 0.38 6.3 ppm 0.75 0.42   0 ppm100.00 100.00

The results in Tables 5 and 5A demonstrate that under the conditionsdescribed, biocide produced by mixing guanidinium sulfate with dilutehypochlorite is less efficacious than biocide produced by first mixingguanidium sulfate and sodium bromide, and then mixing this mixture withdilute hypochlorite.

Example 6 Efficiency of Production of the Biocide

Residual total chlorine was measured in all of the control tests(biocide in DI water) of Tests 1-6 described above. The results arepresented in Table 6.

TABLE 6 % Cl₂ - 10 min % Cl₂ - 20 Hours test 1 (Shim et al.) 59.5 54.8test 2 (Shim et al.) 40.5 26.2 test 3 (Shim et al.) 48.8 38.1 test 4(Shim et al.) 48.8 54.9 test 5 119 107.1 test 6 88.1 78.6

The results in Table 6 show that the “stabilized hypochlorite” andbiocides produced in accordance with Shim et al. have a low initialresidue compared to biocides formed in accordance with embodiments ofthe present invention. This demonstrates degradation of the biocide ofShim et al. during its production. In several instances the biocidesproduced by the method of Shim et al. also degrade faster during thefirst 20 hours after addition to the water to be treated.

Series 2

Reaction media were similar to the media described in Series 1.

Example 7 Comparison of Treatment of Aerobic and Anaerobic BacteriaUsing Ammonium Carbamate and Ammonium Carbonate

Biocides were prepared from sodium hypochlorite and either ammoniumcarbamate or ammonium carbonate in the presence and absence of sodiumbromide, as described hereinbelow, and immediately added to the samplesto be treated. The test containers were inoculated with MOs 48 hoursprior to addition of biocide.

Ammonium carbonate solution was prepared in DI water (11.71 g ammoniumcarbonate in 100 ml DI water) and further diluted in DI water to a finalconcentration of 4680 ppm. Sodium hypochlorite was diluted in DI water(to a concentration of 4200 ppm, 0.42% w/v expressed as total chlorine).As described above, the dilutions were mixed to provide equimolaramounts of hypochlorite and ammonium carbonate to form a biocide (2100ppm as total chlorine), appropriate volumes of which were immediatelyadded to the test containers.

In an analogous manner, ammonium carbamate was prepared in DI water(11.71 g ammonium carbamate in 100 ml DI water) and further diluted inDI water to a concentration of 4680 ppm, and mixed with a dilutesolution of sodium hypochlorite (4200 ppm, 0.46% w/v expressed as totalchlorine), and appropriate volumes of the resulting biocide (2100 ppm astotal chlorine) were immediately added to the test containers.

ATP was measured 25 minutes and 120 minutes after feeding the biocide.Residual total chlorine was measured 5 minutes after feeding thebiocide, and samples for viable counts were taken after 30 minutescontact time.

The tests were repeated, this time with mixing of sodium bromide (6200ppm) with the ammonium carbonate or ammonium carbamate prior to mixingwith the sodium hypochlorite.

Counts of ATP, total aerobic bacteria, growth on a high sugar growthmedium, and killing of anaerobic bacteria were measured. The results arepresented in Tables 7A-7E.

TABLE 7A Comparison of ATP levels (ng/ml) measured after 25 min AmmoniumAmmonium ammonium ammonium carbamate + treatment carbonate carbonate +NaBr carbamate NaBr 1.4 ppm 25.87 30.7 2.8 ppm 20 17.2 19.2 13.5 5.6 ppm8.8 21.2 10.13 26.7 8.4 ppm 16 6.7  14 ppm 2.6 2.3 3.33  28 ppm 1.591.16 Blank 15.6 40

TABLE 7B comparison of ATP levels (ng/ml) measured after 120 min -regrowth potential Ammonium Ammonium ammonium ammonium carbamate +Treatment carbonate carbonate + NaBr carbamate NaBr 1.4 ppm 89.3 66.72.8 ppm 101.3 109.3 81.33 117.33 5.6 ppm 41.3 29.3 23.3 23.33 8.4 ppm8.9 2.5  14 ppm 1.43 0.77 1.05  28 ppm 0.47 0.22 Blank 94.7 110.7

TABLE 7C comparison of total aerobic bacteria count, cfu/ml after 30 mincontact time ammonium ammonium ammonium carbonate + ammonium carbamate +Treatment carbonate NaBr carbamate NaBr 1.4 ppm 3.00 × 10⁸ 5.00 × 10⁷2.8 ppm 5.00 × 10⁷ 2.70 × 10⁷ 1.10 × 10⁷ 2.40 × 10⁷ 5.6 ppm 5.00 × 10⁶9.44 × 10⁶ 7.60 × 10⁶ 3.20 × 10⁶ 8.4 ppm 4.00 × 10⁶ 6.60 × 10⁴  14 ppm3.20 × 10⁵ 3.60 × 10⁴ 2.80 × 10⁵  28 ppm 4.40 × 10⁴ 4.16 × 10⁴ Blank4.80 × 10⁷ 4.80 × 10⁷ 4.60 × 10⁷ 4.60 × 10⁷

TABLE 7D comparison of growth on a high sugar growth medium (cfu/ml),after 30 min contact time ammonium ammonium ammonium carbonate +ammonium carbamate + Treatment carbonate NaBr carbamate NaBr 1.4 ppm3.00 × 10⁷ 3.00 × 10⁷ 2.8 ppm 3.00 × 10⁷ 1.22 × 10⁵ 1.10 × 10⁵ 4.00 ×10³ 5.6 ppm 3.00 × 10⁷ 1.80 × 10⁴ 1.00 × 10² 1.00 × 10³ 8.4 ppm 3.00 ×10⁴ 1.00 × 10¹  14 ppm 2.00 × 10² 1.00 × 10¹ 1.00 × 10¹  28 ppm 2.00 ×10² 2.00 × 10¹ Blank 5.00 × 10⁷ 3.00 × 10⁸

TABLE 7E total anaerobic counts (cfu/ml), after 30 min contact timeammonium ammonium ammonium ammonium carbamate + Treatment carbonatecarbonate + NaBr carbamate NaBr 1.4 ppm 3.00 × 10⁷ 2.8 ppm 2.00 × 10⁶1.00 × 10⁴ 3.00 × 10⁷ 1.00 × 10³ 5.6 ppm 5.00 × 10⁶ 2.10 × 10⁴ 3.40 ×10⁴ 1.00 × 10³ 8.4 ppm 2.00 × 10³ 3.00 × 10³  14 ppm 1.00 × 10² 1.00 ×10¹ 2.00 × 10²  28 ppm 1.00 × 10² 1.00 × 10¹ 1.00 × 10² Blank 3.00 × 10⁷3.00 × 10⁷

Series 3 Example 8 Comparison of Biocidal Properties of BiocidesPrepared from Ammonium Sulfamate, Ammonium Sulfate, Sulfamic Acid andAmmonium Carbamate

Reaction medium: 4 liters DI water containing 200 ml cooked starch, 5.29g NaHCO₃, and 0.52 g CaO. The pH was adjusted with HCl to 8.23.

As described in earlier examples, biocides were prepared as follows:

Test 9: Sulfamic acid solution (14.62 g sulfamic acid in 100 ml DIwater) was diluted (4 ml of solution in 100 ml DI water) and NH₃ (0.5ml, 25% w/v in water) was added. Diluted NaOCl (4 ml of a solutioncontaining 14% w/v NaOCl as Cl₂ were diluted in 100 ml DI water) wasmixed with the diluted sulfamic acid.

Test 10: Ammonium sulfate solution (19.8 g/100 ml DI water) was diluted(2 ml of solution/100 ml DI water). NaOCl solution (14% w/v as Cl₂ inwater) was diluted in DI water (4 ml of solution/100 ml), and mixed withthe diluted ammonium sulfate solution.

Test 11: Sulfamic acid solution (14.62 g/100 ml DI water) was diluted (4ml solution/100 ml DI water) and mixed with diluted NaOCl (4 ml of 14%w/v as Cl₂ NaOCl solution/100 ml DI water).

Test 12: Ammonium carbamate solution (11.55 g/100 ml DI water) wasdiluted (4 ml solution/100 ml DI water) and mixed with diluted NaOCl (4ml of 14% w/v as Cl₂ NaOCl solution/100 ml DI water).

In tests 9-12, an appropriate volume of the resulting biocide wasimmediately added to water containing MOs from pink slime, as describedabove, and the total residual chlorine in the treated water/medium wasmeasured after 5 minutes and 12 hours. Results are presented in Tables8A and 8B.

TABLE 8A Total residual chlorine after 5 minutes (ppm): feed 5 min 5 min5 min 5 min as Cl₂ (ppm) H₂NSO₃NH₄ (NH₄)₂SO₄ H₂NSO₃H H₂NCO₂NH₄ 1.4(control - 1.4 1.6 0.9 1.2 DI water only) 1.4 0 0 0.3 0 2.8 1.3 0.9 0.70.2 7   4.9 5 4 1.3 14   10.7 8.1 10.7 10.2

TABLE 8B Total residual chlorine after 12 hours (ppm): feed 12 hours 12hours 12 hours 12 hours as Cl₂ (ppm) H₂NSO₃NH₄ (NH₄)₂SO₄ H₂NSO₃HH₂NCO₂NH₄ 1.4 (control - 1.1 1.1 0.9 1.2 DI water only) 1.4 0 0 0.3 02.8 0.1 0 0.3 0.2 7   1.1 1.2 2.9 1.3 14   4.1 3.8 9.2 3.9

The results in Tables 8A and 8B show that the biocides derived fromsulfamic acid and from ammonium sulfamate were the most stable biocidesafter 5 minutes. The biocide derived from sulfamic acid remained stableand exhibited high residual total chlorine after 12 hours.

ATP values for MOs growing on growth medium treated with the biocidesproduced in Tests 9-12 were obtained 30 minutes and 12 hours afteraddition of biocide to the growth medium. The results are shown inTables 8C and 8D.

TABLE 8C ATP measured 20 minutes after feeding the biocide (rlu) feedATP-20 min ATP-20 min ATP-20 min ATP-20 min as Cl₂ (ppm) H₂NSO₃NH₄(NH₄)₂SO₄ H₂NSO₃H H₂NCO₂NH₄ 1.4 25500 24000 31500 39000 2.8 19500 2850026000 16500 7   9950 16000 26000 14000 14   5200 2850 12000 4500 Blank24500 20500 37000 29000

TABLE 8D ATP measured 12 hours after feeding the biocide (rlu) feedATP-12 h ATP-12 h ATP-12 h ATP-12 h as Cl₂ (ppm) H₂NSO₃NH₄ (NH₄)₂SO₄H₂NSO₃H H₂NCO₂NH₄ 1.4 90000 94500 83000 87500 2.8 8550 6000 76000 39507   435 460 42000 560 14   380 390 14500 300 blank 87500 90000 9550095500

Conclusions: at a feed level of 1.4 ppm, no control was achieved, andthe MOs continued to grow. A feed level of 2.8 ppm as total chlorine wasineffective for biocide formed from sulfamic acid, despite the higherresidual left in the process water. At 2.8 ppm, better control wasachieved with ammonium sulfate compared to sodium sulfamate, and stillbetter control with ammonium carbamate after 30 minutes as well as after12 hours.

The test samples of Tests 9-12 were checked for viable counts ofaerobic, anaerobic and high-sugar MOs (cfu/ml) after a contact time of30 minutes. The results are presented in Tables 8E-8G.

TABLE 8E Effect of biocides on growth of aerobic MOs, contact time 30minutes feed aerobic MOs (cfu/ml), 30 minutes as Cl₂ (ppm) H₂NSO₃NH₄(NH₄)₂SO₄ H₂NSO₃H H₂NCO₂NH₄ 1.4 1.29 × 10⁶ 1.40 × 10⁶ 1.08 × 10⁶ 9.70 ×10⁵ 2.8 6.16 × 10⁵ 6.40 × 10⁵ 5.40 × 10⁵ 8.96 × 10⁵ 7   4.00 × 10⁵ 3.60× 10⁵ 8.08 × 10⁵ 5.84 × 10⁵ 14   2.40 × 10⁵ 1.80 × 10⁵ 7.36 × 10⁵ 7.50 ×10⁴ blank 1.20 × 10⁶ 1.44 × 10⁶ 1.10 × 10⁶ 1.34 × 10⁶

TABLE 8F Effect of biocides on growth of anaerobic MOs, contact time 30minutes feed Anaerobic MOs (cfu/ml), 30 minutes as Cl₂ (ppm) H₂NSO₃NH₄(NH₄)₂SO₄ H₂NSO₃H H₂NCO₂NH₄ 1.4 1.50 × 10³ 1.00 × 10¹ 2.50 × 10³ 1.00 ×10¹ 2.8 1.00 × 10¹ 1.00 × 10¹ 1.00 × 10¹ 1.00 × 10¹ 7   1.00 × 10¹ 1.00× 10¹ 2.00 × 10² 1.00 × 10¹ 14   1.00 × 10¹ 1.00 × 10¹ 3.00 × 10² 1.00 ×10¹ blank 1.00 × 10³ 1.00 × 10³ 1.00 × 10³ 1.00 × 10³

TABLE 8G Effect of biocides on growth of high-sugar MOs, contact time 30minutes feed High sugar MOs (cfu/ml), 30 min as Cl₂ (ppm) H₂NSO₃NH₄(NH₄)₂SO₄ H₂NSO₃H H₂NCO₂NH₄ 1.4 6.24 × 10⁴ 1.03 × 10⁵ 6.40 × 10⁴ 1.79 ×10⁵ 2.8 5.00 × 10² 4.00 × 10² 3.32 × 10⁴ 2.00 × 10² 7   1.00 × 10¹ 1.00× 10¹ 8.72 × 10⁴ 1.00 × 10¹ 14   1.00 × 10¹ 1.00 × 10¹ 7.30 × 10³ 1.00 ×10¹ Blank 1.20 × 10⁵ 1.10 × 10⁵ 7.00 × 10⁴ 1.10 × 10⁵

The results shown in Tables 8E-8G clearly show differences in viablecounts after a contact time of 30 minutes. The biocide produced fromammonium carbamate was superior to the other biocides tested incontrolling aerobic MOs.

Series 4 Example 9 Comparison of Biocidal Properties of BiocidesPrepared from Different Nitrogen-Containing Compounds or Salts

Test medium A: 500 ml of contaminated clay suspension and 200 ml ofcooked starch was mixed with 5 liters of tap water and inoculated withbiofilm removed from a paper mill surface area.

Test medium B: 0.46 g sodium sulfide was added to 2 liters of the clayslurry of Test medium A.

Due to the high turbidity of the samples, reliable measurement ofresidual total chlorine was not possible. Qualitative measure of totalchlorine confirmed that most of the biocide was consumed by this testmedium.

Samples for viable counts were removed after a contact time of 1 hour.

As described above, biocides were prepared by mixing dilutions of thefollowing with diluted sodium hypochlorite:

Test molar ratio to No. species NaOCl 13 mixture of glycine and ammoniumhydroxide 1:1 14 ammonium sulfamate 1:1 15 methyl carbamate 1:1 16N,N-dimethyl ammonium N,N-dimethyl 1:1 carbamate 17 ammonium carbamate +HCl (HCl was added to 1:1 ammonium carbamate prior to mixing with NaOCl,to ensure biocide production at a pH of 9.2) 18 ammonium sulfate 2:1 19ammonium sulfate 2:1 20 ammonium carbamate + HCl (HCl was added to 1:1ammonium carbamate prior to mixing with NaOCl, to ensure biocideproduction at a pH of 8.7) 21 control —

The biocides formed were immediately added in appropriate volumes to thetest samples and the concentrations of aerobic and anaerobic MOsmeasured. pH was measured at the time of application of the biocide andtwo days later. The concentrations at which biocides were applied andthe results of biocide application to test medium A are presented inTable 9A; the concentrations at which biocides were applied and theresults of biocide application to test medium B are presented in Table9B.

TABLE 9A Feed level TEST (as Cl₂, ppm) aerobic anaerobic pH day 1 pH day3 13CA 12 1.10 × 10⁵ 1.24 × 10⁴ 7.5 7.3 13CB 20 1.10 × 10⁵ 1.04 × 10⁴7.71 7.58 14CA 12 8.10 × 10⁴ 2.00 × 10³ 7.42 7.58 14CB 20 3.30 × 10⁴8.20 × 10² 7.43 7.38 15CA 12 8.90 × 10⁴ 8.00 × 10³ 7.38 7.49 15CB 208.20 × 10⁴ 3.64 × 10³ 7.56 7.56 16CA 12 1.50 × 10⁵ 2.00 × 10¹ 7.65 7.416CB 20 8.60 × 10⁴ 1.00 7.75 7.37 17CA 12 8.90 × 10⁴ 1.00 × 10 7.66 7.6117CB 20 1.70 × 10⁴ 1.00 8.04 7.44 18CA 12 9.00 × 10⁴ 6.80 × 10³ 7.417.23 18CB 20 3.30 × 10⁴ 1.44 × 10³ 7.45 7.52 19CA 12 1.90 × 10⁵ 1.007.45 7.32 19CB 20 1.20 × 10⁵ 2.00 × 10 7.53 7.27 20CA 12 1.90 × 10⁵ 2.00× 10 7.52 7.29 20CB 20 1.80 × 10⁵ 3.60 × 10³ 7.78 7.4 21C 0 9.90 × 10⁵1.00 × 10⁴ 7.44 7.26

TABLE 9B Feed level pH TEST (as Cl₂, ppm) aerobic anaerobic pH day 1 day3 13SA 20 2.20 × 10⁵ 3.00 × 10⁴ 8.18 7.43 13SB 24 1.60 × 10⁵ 3.00 × 10⁴8.29 7.35 14SA 20 4.50 × 10⁴ 1.70 × 10² 8.31 7.66 14SB 24 2.50 × 10⁴2.60 × 10³ 8.48 7.46 15SA 32 9.50 × 10⁴ 3.00 × 10⁴ 8.49 7.63 15SB 367.60 × 10⁴ 3.00 × 10⁴ 8.64 8.47 16SA 32 1.60 × 10⁵ 1.00 8.29 7.6 16SB 361.50 × 10⁵ 1.00 8.49 7.57 17SA 32 8.70 × 10³ 1.00 8.74 8.68 17SB 36 6.60× 10³ 1.00 8.85 8.82 18SA 20 2.40 × 10⁵ 3.00 × 10⁴ 8.01 7.35 18SB 241.40 × 10⁵ 3.00 × 10⁴ 8.24 7.58 19SA 32 3.00 × 10⁴ 1.00 8.35 8.36 19SB36 1.70 × 10³ 1.00 8.41 8.48 20SA 32 1.60 × 10⁴ 1.00 8.63 8.6 20SB 368.10 × 10³ 1.00 8.67 8.64 21S (control) 0 9.20 × 10⁵ 3.00 × 10⁴ 7.8 7.37

The results presented in Tables 9A and 9B show that in spite of the highdemand for oxidizer in the media, and the trace residual chlorinemeasured using the given biocide feed levels, biocides produced fromammonium carbamate and ammonium sulfamate controlled the growth of MOsin the heavily infested samples.

Series 5

Two test media were used:

CLAY: 200 ml of clay suspension was added to 2 liters of tap water at pH7.04. Test medium was inoculated with MOs from a paper mill

CLAY+ACID: 200 ml of clay suspension was added to 2 liters of tap waterand the pH was reduced to 6.12 by addition of HCl. Starch (100 ml cookedstarch) was added. The test medium was not inoculated with external MOs.

All test samples were fed with 20 ppm biocide as total chlorine.

Example 10

As described above, biocides were prepared by mixing dilutions of thefollowing and dilute sodium hypochlorite:

Test No. species molar ratio to NaOCl 22 Control - no biocide 23ammonium carbamate 1:1 24 ammonium sulfate 1:1 25 ammonium carbonate 1:126 ammonium carbamate + HCl 1:1 (HCl added to reduce pH to 9.22)

Appropriate amounts of the biocides formed were immediately added to thetest samples and aerobic and anaerobic viable counts were measured 60minutes after application. pH was measured at the time of application ofthe biocide and three days later. The concentrations at which biocideswere applied and the results of biocide application are presented inTable 10.

TABLE 10 Conc. (as Cl₂, pH TEST conditions ppm) aerobic anaerobic day 1pH day 3 22A clay + acid 0 5.00 × 10⁴ 1.02 × 10⁴ 6.64 Data not available22C clay 0 1.50 × 10⁷ 6.00 × 10³ 7.4 7.22 23CB clay 20 3.00 × 10⁶ 2.12 ×10³ 7.55 7.82 23AB clay + acid 20 3.08 × 10⁴ 5.28 × 10³ 6.93 7.06 24CBclay 20 8.00 × 10⁵ 2.00 × 10³ 7.34 7.16 24AB clay + acid 20 2.80 × 10⁴8.56 × 10³ 6.6 7.05 25CB clay 20 3.00 × 10⁶ 1.84 × 10³ 7.41 7.24 25ABclay + acid 20 1.09 × 10⁴ 4.96 × 10³ 6.76 7.03 26CB clay 20 3.00 × 10⁷2.52 × 10³ 7.72 7.34 26AB clay + acid 20 5.40 × 10⁴ 1.60 × 10⁴ 6.88 6.69

Series 6

Reaction media: 0.34 g of Na₂S were added to 2 liters of tap watercontaining 200 ml cooked starch slurry. Initial ORP: −263 mv. As thestarch was naturally inoculated, this test medium was not inoculatedwith an external culture of microorganisms.

Example 11

By analogy to Example 9, biocides were prepared using the followingspecies and sodium hypochlorite in the following ratios:

molar ratio to Test No. species NaOCl 27 ammonium carbonate 1:1 28ammonium cyanurate 1:1 29 ammonium sulfamate 1:1 30 ammonium carbamate1:1 31 1:1 mixture of ammonium carbamate 1:1 and carbamic acid (HCladded to lower pH to 9.2) 32 ammonium bromide 1:1 33 ammonium carbamate2:1 34 control —

Results, including total chlorine, are shown in Table 11:

TABLE 11 Feed level (as total chlorine TEST Cl₂, ppm) (ppm) aerobicanaerobic pH day 1 pH day 3 pH day 4 27A 47 2.5 8.80 × 10⁵ 1.00 8.948.85 7.67 28A 47 0.9 3.00 × 10⁶ 1.00 8.88 7.98 7.5 29A 47 1.2 3.00 × 10⁶1.00 8.83 7.99 7.43 30A 47 6 5.12 × 10⁵ 1.00 9.12 9.1 8.19 31A 47 1.52.00 × 10⁶ 1.00 8.94 8.3 7.55 32A 47 2.4 1.00 × 10⁶ 1.00 8.88 8.79 7.5833A 47 4.9 1.50 × 10³ 1.00 9.1 9.07 8.71 34A 0 0 8.00 × 10⁶ 1.00 8.517.72 7.45

This experiment presents a special case of extremely high demand for anoxidizer exerted by the presence of a strong reducing agent (Na₂S) andstarch and degradation byproducts thereof which are produced by theheavy microbial population that infests starch. Extreme conditions suchas these may frequently be found in industrial and agriculturalenvironments, such as soil, recycling processes, activated sludge andwaste and the like.

Example 12

Biocides were prepared by analogy to Example 9, but the biocides wereapplied to a clay slurry, as described in Example 10, and additionalbiocides were prepared in the same way but wherein NaBr (equimolar tohypochlorite and nitrogen-containing compound or salt thereof) was addedto the nitrogen-containing compound or salt thereof prior to dilutionand mixing with the hypochlorite dilution. Results are shown in Tables12A and 12B.

TABLE 12A TEST Conc. (as Cl₂, ppm) Aerobic anaerobic 13CA 12 1.10 × 10⁵1.24 × 10⁴ 13CB 20 1.10 × 10⁵ 1.04 × 10⁴ 14CA 12 8.10 × 10⁴ 2.00 × 10³14CB 20 3.30 × 10⁴ 8.20 × 10² 15CA 12 8.90 × 10⁴ 8.00 × 10³ 15CB 20 8.20× 10⁴ 3.64 × 10³ 16CA 12 1.50 × 10⁵ 2.00 × 10  16CB 20 8.60 × 10⁴ 1.0017CA 12 8.90 × 10⁴ 1.00 × 10  17CB 20 1.70 × 10⁴ 1.00 18CA 12 9.00 × 10⁴6.80 × 10³ 18CB 20 3.30 × 10⁴ 1.44 × 10³ 19CA 12 1.90 × 10⁵ 1.00 19CB 201.20 × 10⁵ 2.00 × 10¹ 20CA 12 1.90 × 10⁵ 2.00 × 10¹ 20CB 20 1.80 × 10⁵3.60 × 10³ 21C 0 9.90 × 10⁵ CA, CB = no NaBr added during biocideproduction

TABLE 12B TEST Conc. (as Cl₂, ppm) Aerobic anaerobic 13CC 20  9.30 × 1048.96 × 10³ 13CD 28 9.60 × 10⁴ 1.04 × 10³ 14CC 20 1.10 × 10⁵ 1.46 × 10³14CD 28 9.00 × 10⁴ 1.52 × 10² 15CC 20 6.80 × 10⁴ 8.00 × 10³ 15CD 28 4.80× 10⁵ 2.72 × 10³ 16CC 20 6.60 × 10⁴ 1.00 16CD 28 3.80 × 10⁴ 1.00 17CC 205.00 × 10⁴ 2.00 × 10 17CD 28 1.50 × 10⁴ 1.00 18CC 12 3.90 × 10⁴ 2.00 ×10³ 18CD 20 1.30 × 10⁴ 6.40 × 10² 19CC 20 1.90 × 10⁵ 2.00 × 10¹ 19CD 285.90 × 10⁴ 4.00 × 10¹ 20CC 20 8.00 × 10⁴ 1.00 × 10⁰ 20CD 28 1.20 × 10⁴1.00 × 10¹ 21C 0 9.90 × 10⁵ CC, CD = NaBr added during biocideproduction

Series 7 Reduction of Na₂S

A series of containers each containing 100 ml DI water in which ˜5 mg ofsodium sulfide was dissolved were prepared. To each container anappropriate amount of an oxidizer or a control solution was added asfollows:

-   a. 0.08 g NaNO₂-   b. ammonium carbamate (110 mg)-   c. Monochloroamine (MCA) formed from ammonium sulfate and NaOCl (1:1    molar ratio, each component pre-diluted before mixing, 15 ppm as    total chlorine).-   d. MCA formed from ammonium sulfate and NaOCl (1:1 molar ratio, each    component pre-diluted before mixing, 15 ppm as total    chlorine)+ammonium carbamate (110 mg).-   e. Reaction product of ammonium carbamate and sodium hypochlorite    (15 ppm as total chlorine) (1:1 molar ratio)+100 ppm ammonium    carbamate-   f. Reaction product of ammonium carbamate and sodium hypochlorite    (15 ppm as total chlorine), molar ratio 2:1-   g. Reaction product of ammonium carbamate and sodium hypochlorite    (15 ppm as chlorine), molar ratio 1:1-   h. Reaction product of ammonium bromide and sodium hypochlorite (15    ppm as chlorine), molar ratio 1:1, +ammonium carbamate (100 mg).-   i. Reaction product of ammonium bromide and ammonium carbamate with    sodium hypochlorite (15 ppm as chlorine), molar ratio 1:1:1

Samples were analyzed for total sulfur and for sulfate several daysafter addition of oxidizer. The results are presented in Table 13:

TABLE 13 Test % S remaining % SO₄ formed A 100 0 B 19.6 45.63 C 3.9237.1 D <2 24.7 E 2 <16.9 F 3.9 16.9 G 1.96 13 H 17.6 50.8 I 15.7 24

The results in Table 13 demonstrate that ammonium carbamate can removesulfides, and that upon reaction with NaOCl or with mixtures containingchloramines, ammonium carbamate retains high efficacy in removingsulfides from the treated samples.

Series 8 Reactions of Nitrogen-Containing Compounds

Reaction Media:

-   SAND: 250 g sand was added to 2.5 l tap water containing 100 g    contaminated starch.-   ASA: 150 ml CaCO₃ slurry and 20 ml Bayer size ASA (alkenyl succinic    anhydride). The slurry was inoculated with pieces of slime from a    paper mill. 1 ml OBA (Optical brightening agent, a Triazine    derivative) was added to each 100 ml of the test solution.

The following nitrogen-containing compounds or salts were tested:

Test 35=Dimethyl hydantoin (DMH)+NH₄OH

Test 36=ammonium carbamate

Test 37=ammonium sulfamate

Test 38=sulfamic acid

Test 39=glutamine

Test 40=ammonium chloride

Test 41=ammonium bromide

Test 42=blank

Each nitrogen-containing compound or salt was mixed with diluted NaOCl,and the reaction product was added to the reaction container in theappropriate amount as soon as the biocide was prepared. Prior toaddition to the reaction container, the biocide contained 4000 ppm astotal chlorine.

The results of tests in SAND (sand+starch) are presented in Table 14:

TABLE 14 feed total N-cont. level chlorine 10 min. aerobic anaerobic Cl₂after pH after cmpd. (ppm) (ppm) (cfu) (cfu) 1 h (ppm) three weeks 40 83 7.50 × 10⁴ 3.00 × 10 4.3 6.97 40 12 6 1.68 × 10⁴ 4.00 × 10 7.5 6.89 358 5.6 1.84 × 10⁴ 1.00 × 10 4.3 6.84 35 12 7.5 8.80 × 10² 2.00 × 10 6.86.94 36 8 4.9 4.40 × 10³ 6.00 × 10 4.8 6.9 36 12 7.2 6.00 × 10² 1.00 ×10 6.8 7.46 37 8 5.6 1.02 × 10³ 5.00 × 10 5.3 6.9 37 12 8.3 7.00 × 10²1.00 × 10 7.6 6.88 38 8 1.9 2.00 × 10⁵ 1.00 × 10⁴ 1.1 5.15 38 12 2.71.50 × 10⁵ 6.00 × 10³ 2 5.79 39 8 6.1 3.00 × 10⁶ 3.00 × 10⁴ 1.9 4.12 3912 8.4 3.00 × 10⁶ 3.00 × 10⁴ 3.4 4.07 40 8 5 1.07 × 10³ 3.00 × 10 4 6.7840 12 8.5 5.00 × 10² 2.00 × 10 7.1 6.84 42 control 0 0 1.15 × 10⁷ 5.92 ×10⁴ 0 4.25

The results of tests in ASA (CaCO₃+ASA) are presented in Table 15:

TABLE 15 total feed chlorine pH after N-cont. level 10 min. aerobicanaerobic Cl₂ after three cmpd. (ppm) (ppm) (cfu) (cfu) 1 h weeks 40 85.3 2.82 × 10⁵ 1.00 5.1 7.53 40 12 8 9.52 × 10⁴ 1.00 × 10 8.2 7.63 35 84.9 1.50 × 10⁵ 1.00 4.2 7.6 35 12 7.5 8.16 × 10⁴ 1.00 × 10 7.5 7.67 36 85.3 1.00 × 10⁵ 3.00 × 10 4.5 7.59 36 12 5.3 1.00 × 10⁵ 1.00 × 10 4.27.62 37 8 4.8 1.50 × 10⁵ 2.00 × 10 4.7 7.55 37 12 8.2 1.00 × 10⁵ 1.00 ×10 8 7.82 38 8 1.1 3.00 × 10⁶ 3.00 × 10³ 1.2 7.52 38 12 1.1 3.00 × 10⁵2.20 × 10³ 2.3 7.48 39 8 5.3 3.00 × 10⁵ 3.00 × 10⁴ 2.8 7.41 39 12 7.63.00 × 10⁶ 3.00 × 10⁴ 3.9 7.39 40 8 3.9 1.50 × 10⁵ 2.00 × 10 4.5 8.24 4012 5.9 3.20 × 10⁴ 1.00 × 10 7.9 8.16 42 control 0 0 5.84 × 10⁶ 1.60 ×10⁴ 0 8.23

The results in Tables 14 and 15 show that biocides derived fromcompounds containing an amide moiety, an imide moiety, a sulfamidemoiety, a sulfimide moiety, or an amineimine moiety have a high biocidalactivity even under conditions not favorable to oxidizing biocides. Theefficacy of these biocides is higher than the efficacy exhibited bychloramines derived from inorganic salts.

Series 9 Procedure

Diluted procedure: Biocides were prepared from a solution of sodiumhypochlorite (24,000 ppm as total chlorine) and an equal volume of asolution containing an equimolar amount of a nitrogen-containingcompound or salt thereof. Final concentration of hypochloriteimmediately prior to mixing was therefore expected to be 12,000 ppm.

Concentrated procedure: Biocides were prepared from a solution of sodiumhypochlorite (12,000 ppm as total chlorine) and a negligible volume of aconcentrated solution (ammonium/DMH: 18% w/v; guanidium sulfate, 30%w/v; ammonium carbamate, 35.3% w/v; ammonium sulfamate, 26.1% w/v)containing an equimolar amount of a nitrogen-containing compound or saltthereof. Final concentration of hypochlorite immediately prior to mixingwas therefore expected to be 12,000 ppm.

Biocide pH, concentration and % were measured 20 minutes after mixing ofthe components. The results are shown in Table 16.

TABLE 16 biocide biocide % mode of concentration yield (relativeCompound/salt addition biocide pH ppm as Cl₂ to Cl alone) DMH dil. 12.637500 61.5 DMH conc. 12.65 6000 49.2 Guanidine dil. 12.1 12200 100Guanidine conc. 12.11 11200 91.8 Carbamate dil. 10.57 11300 92.6Carbamate conc. 10.55 9990 81.9 Sulfamic dil. 10.5 3600 29.5 Sulfamicconc. 11.19 3900 32

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims.

1. A method for controlling microbial or biofilm growth in a medium, themethod comprising: mixing ammonium carbamate and an aqueous solution ofa hypochlorite oxidant to form a biocide, wherein the molar ratio ofammonium to hypochlorite is at least 1:1, and applying said biocide tosaid medium, wherein the concentration of said biocide in said medium,upon application of said biocide to said medium, is 1.4-8.4 ppmexpressed as chlorine, and wherein said biocide has a pH of between 9.0and 11.5 immediately prior to being applied to said medium.
 2. A methodaccording to claim 1, wherein the concentration of said hypochloriteoxidant in said aqueous hypochlorite oxidant solution immediately priorto mixing with said ammonium carbamate is not more than 24,000 ppm astotal chlorine.
 3. A method according to claim 1, wherein said ammoniumcarbamate is in an aqueous solution at a concentration of 0.5-60% w/vimmediately prior to mixing with said hypochlorite oxidant solution. 4.A method according to claim 1, wherein said hypochlorite oxidant isselected from the group consisting of alkaline and alkali earth metalhypochlorites, hypochlorite released to water from a stable chlorinecarrier and hypochlorite formed in situ from chlorine gas, and mixturesthereof.
 5. A method according to claim 1, wherein said hypochloriteoxidant is selected from the group consisting of lithium hypochlorite,sodium hypochlorite, calcium hypochlorite, magnesium hypochlorite andpotassium hypochlorite.
 6. A method according to claim 1, wherein saidammonium carbamate is diluted prior to mixing with said hypochloriteoxidant.
 7. A method according to claim 1, wherein said medium is pulpand paper factory process water.
 8. A method according to claim 1,wherein said medium is cooling tower water.
 9. A method according toclaim 1, wherein said medium is waste water or reclaimed waste water.10. A method according to claim 1, wherein said medium is a sludge. 11.A method according to claim 1, wherein said medium is a colloidalsuspension.
 12. A method according to claim 1, wherein said medium isirrigation water.
 13. A method according to claim 1, wherein said mediumis a medium having a high reducing capacity.
 14. A method according toclaim 1, wherein said medium has an ORP of not greater than 150millivolts.
 15. A method according to claim 1, wherein said hypochloriteoxidant and said ammonium carbamate are mixed in the absence of addedbromide and said medium is substantially free of added bromide duringapplication of said biocide.
 16. A method according to claim 1, whereinthe concentration of the biocide immediately prior to being applied tosaid medium is from 1000 to 12000 ppm expressed as total chlorine.
 17. Amethod according to claim 1, wherein the concentration of said biocidein said medium, upon application of said biocide to said medium, is1.4-7 ppm expressed as chlorine.
 18. A method according to claim 1,wherein the biocide is effective within 1 hour of application to saidmedium.
 19. A method according to claim 1, wherein the concentration ofsaid biocide in said medium, upon application of said biocide to saidmedium, is 1.4-5.6 ppm expressed as chlorine.
 20. A method according toclaim 1, wherein the concentration of said biocide in said medium, uponapplication of said biocide to said medium, is 1.4-2.8 ppm expressed aschlorine.
 21. A method according to claim 1, wherein said biocideremains in the liquid phase.